Better to utilize a Vesa 100mmX100mm against the wall mounting plate and put a single or double gang with keystone jacks right next to it hiding it some. It won't look "built in" as much but easy. For the kitchen (and office) I put HD keystone jacks and found a very thin RG6 for OTA HD.
I'm redoing my garage TS right now using a Pivot under the counter mount to a 12" touchscreen (vesa mounted) after replacing two 8 inch automotive style touchscreens which have failed on me after 2 years each.
Check the 12VDC draw on your ELO touchscreens and you'll see its probably over 1 AMP and maybe even 2-3 Amps.
I did similiar for my home office LCD, 2 kitchen LCD's and Laundry room LCD.
I have a friend that had a 55" LCD installed as part of a package when he purchased his condo. The TV guy put a hole behind the LCD and passed the power cable to another hole (actually 120VAC outlet) below the TV. The HD, RG6, Component cables were also just in a hole and passed down inside of the drywall to another hole (very much of a hack job and not code).