I work for a company who manufactures these trailers (www.wanco.com).
Aside from the video and network components, the important things to consider are:
1) choosing the right size solar array to meet your power requirements, which is dependent on your geolocation / sun quality
2) making sure the trailer is simple to deploy and stable both when deployed and when towing
3) making sure you are incorporating the right power infrastructure: charge controller, deep cycle batteries, etc
4) securing your equipment and batteries from theft. Batteries are a hot item on the streets, so a strong enclosure with puck locks, guarded hasps and guard hinges will save you a lot of replacement costs down the line
Wanco has options designed for integrators who want to add their own components to a trailer.
I’d be happy to assist you with pricing and information if you are interested.