Point-to-Point VPN

Pre-sales question...  possibly using 3 Firewalla Gold appliances.

For an gated HOA, I'm wanting to put IP cameras on the entrance/exit gates.. maybe (3) always-on live video cameras (entry gate, exit gate, and entry keypad looking at the driver) and one tag reader (snapshot).  We have two different locations where we would do this.

I'm thinking I could have the cable provider drop an internet connection at each location (1/2 mile apart) and no line-of-site between them.  Purchase wireless cameras and setup a small outdoor wireless network at each location and connect that to a Firewall Gold which connects to the Internet.  Cable provider modem and Firewalla in a water resistant utility box - and I may be able to just hardwire instead of wifi).  Duplicate this at the other site.  

Then at the community clubhouse, install the 3rd Firewall Gold as a VPN server and place the video DVR unit in the temperature controlled environment it needs, but also only have one DVR for all the video instead of two different DVR units.  The DVR would likely sync with a cloud service, especially for the vehicle tag stuff.

For this to work I would need the point-to-point VPN to always be connected and to always reconnect after a power failure or cable network outage.  I would also need the VPN to tunnel everything (DHCP request, etc like it's a LAN bridge).

Would this work or am I missing something?
(I programmed network switches/routers about 20 yrs ago so I have some idea what i'm doing..)

As for why.. because several times a year the gates are hit and damaged, i suspect by lawnmower companies pulling trailer and trying to rush through an open exit gate or a closing entry gate.  We are about to spend $10k to replace two gates...