Could someone help with cost estimate for TC and truck?

I think the same guidance as normal applies. Find the camper and then find out what truck you need. On the low end, you could keep your truck and put a really lightweight camper shell on with a window AC and portable generator. That's probably less than 10K. It goes up from there.

It sounds like you only are looking for somewhere to sleep in the cool so a basic shell with AC and generator should be enough.