That makes sense. Given that the $500 is a one off fee and you won't have to mess around with setting up VPN tunnels, I can see why you went the route you did.
Without an inbound public IP address, it's the only viable option in terms of simplicity.
If that is the case he can setup site-to-site VPN with the Meraki Z1 router and the Cradlepoint modem, and then connect to it via VPN.
With IPv6, I'm really surprised that Verizon would give out NAT'ed IP addresses. Guess they are trying to make a pretty penny!
Fastb,
I have used Meraki Z1 routers for similar situations (remote sites). For example I set several of these up for pet ambulances so the vets had access to internal servers while on the move.
I am not familiar with Crandlepoint modems but if they have an internet Ethernet port, you will be...
I just ordered thee of $146 (http://www.aliexpress.com/item/Hot-Sell-2016-New-Arrival-Rotary-Bullet-PTZ-Camera-with-Onvif-1080P-MINI-PTZ-IP-Camera/32583148851.html) and a PTZ keyboard with a five inch monitor...