Access Control Electrified Lockset- for exterior gate

Everything I've seen so far (electric strikes, maglocks, electric bolts) would require a secondary latch in order to keep the gate closed while unlocked.  This would be needed to prevent wind from swinging the gate open and closed.  I could use the existing thumb latch.  The problem is that exiting while locked becomes clunky because you'd have to do two things at once, electrically unlock and simultaneously use the thumb latch; not ideal.  So I think the best option is to use an electrified lockset similar to this:
For this simple control can the ELK control this directly via the form C relay or would I need the ELK-M1KAM?
Can I add a simple wiegand waterproof rfid keypad to the ELK?  
I was thinking I might even make it its own area for independent control.  I think this would give the capability to arm/disarm the entire system with one code or just that area with a second code?  Ill add a standard door sensor to monitor it should make a pretty good setup.  Am I missing anything?
Electrified handsets aren't weatherproof or conformal coated. The internal solenoid will most likely be your achilles heel in using one outdoors.

Depending on the gate, you'd be looking at getting a REX device built in or fabricated by yourself that would be triggered by the thumb latch. 
You could go with a mag and do a read in/out (2 readers).
Depending on the emergency egress needs, I'd consider a maglock with built in DSM.
You could also install a pneumatic rex button to address the unlock issue.
I couldnt find anything about the handsets being waterproof either.  The reason I thought it would work is because the local access control company installed two at my work.  Both are outside and very exposed.  More exposed than mine in fact.  The fences at work are expanded metal where mine are solid composite wood slats.  At work, one was installed about 4 years ago and it has worked flawlessly.  It is not marked with a brand except for a capital G with a line under it on the deadlatch plate.  I popped the knob off yesterday when nobody was looking and still couldnt find a manufacturer.  I didnt disassemble any further than that.  The other just got installed two weeks ago and is clearly a Schlage handset.
Emergency egress is not needed.  It's just my backyard and the gate was never there to start with.  It's something I added.
I kinda like the idea of a thumb latch with REX built in.  I could then have the alarm short the REX with a relay so that it can't be opened.  Disarm the alarm and the REX becomes active again.
I could use a keypad to momentarily re-enable the REX or disarm the area.  I could place a push button on the inside to momentarily activate the REX.
Is that a total "charlie-foxtrot"?  Is there a more elegant way that I'm missing?
What would a thumb latch REX look like?  Simple micro-switch?
The more I think about the complexity of that I'm not sure what the reliability benefit would be.  There are a lot more pieces to the puzzle.
The thumb latch REX wouldnt be normal because it's available to both sides.  The inside override would be more like a traditional REX.  I suppose it would be a PIR to prevent the need to do two things at once.
Trine is reasonably decent stuff. We use them for oddball items.
Recommended application for a strike, the problem you're going to have no matter what is if you require the gate to remain unlocked, you'll need to provide an auxiliary method to keep the gate closed also.

I wouldn't put a PIR outside. I don't know the physical application here or the need to have one. I'd still recommend a prox unit or keypad that spits weigand to the M1.
If you're putting a strike, the unsecure side is always going to be locked, so you need to provide a way to release it from outside, the inside will always be free egress.
As far as outdoor, usually it's a matter of luck and the environment. Electrified hardware doesn't survive in my area unless it's conformal coated or potted and sealed. Sometimes it's also luck. This is coming from someone who works on multiple sites, one of which has <1800 access controlled points.
What I meant was I would leave the strike locked full time. This would negate the need for an auxiliary method to keep the gate closed.
Alarm armed - Instead of having the M1 actually lock the strike, I would simply have it deactivate the outside PIR.  No entry from the outside and free escape from the inside.
Alarm disarmed - The strike will still be locked but the PIR will be active providing touch-less entry.  Also useful for when my hands are full.  From the outside PIR grants entry.  From the inside, the lockset lever functions as normal and allows free escape.
I guess the (NC) alarm relay, PIR, and strike would be in series.  
With a KAM and electrified hardware, you would use that to fire the strike, no additional special wiring other than to the KAM and something to put a short across the supervisory relay (Elk's REX are NC circuit, contrary to industry standard).
Either way, you'd wire the contact (recommended) access relay and REX separately.
I'd probably look at something other than a PIR to fire the lock. Keep in mind, outdoor is tough to begin with, now you're going to be firing the unlock relay and hardware every time it faults.
Thanks for the feedback.  I'll consider a push button or similar to replace the PIR.  Forgive my ignorance, what is the supervisory relay for?  Is this just to check the door status to make sure it's not opened when it shouldnt be?
Contact would be used to determine the position of the door, conversely, it's typically used for relock purposes, access grant>door opens>system relocks door, otherwise it's just depending on a timeout, which can have the gate bounce out of the lock or whatever else could possibly happen.