Best security cameras for travel trailer?

I think you need to get the hotspot situation solved first. Once that is solved, the security cameras can pretty much be anything you want. Try looking at visible.com and their "party plan". From what I understand you can own all the phones on the party plan, that would include a dedicated line for your security system. Something that you might be interested in. They claim to have an unlimited data plan with no throttling which is hard to find for a reasonable price.