I assume by "not a name brand" and "custom built" referring to home built or otherwise not by a camper manufacture?
But as to insuring, were in CA. Camper requires neither title or registration, on its own I imagine it would be difficult to find off the shelf insurance compared to a MH or TT. Truck camper is cargo covered by the policy on truck. When bought new our truck ins satisfied lender requirement. (I don't know how that worked as camper was worth truck value but premium only went up a few $).
Later when we switched ins, camper paid off, we had requested it to be specifically added to truck policy. Few years later when we claimed against it they covered repair expenses-it was noted that camper was never added to policy but they had record of the request & agreement to add. Next bill went a up a few dollars and a single sentence was added that says
"This truck carries an on board camper" Thats it.
When originally added value was set $20,000 by answering the question, Whats it worth?. Name, feature, nothing else was asked.
The paying for a place to stay etc- Idunno, unless your truck has ins
that covers that. We had something like that on our old MH for a while but paid dearly for it. Like AAA roadside but it included some extras. Id assume again on truck?
My only suggestion at this point would be a local RV shop that sells TCs-might even contact Good Sam. Farmers or Allstate. tried the links on the NADA site that leads to Progressive-but it dead ends once you get to RV type selection. However alot of folks use progressive
One of many-An older
thread, if value etc is against brand you might have to get appraised by some? source that would satisfy ins. Mention to your Geiko agent your probably be changing companies to get camper covered-they might send someone out? Affordable cost wise would probably be simple liability while in truck, the replacement for value-reimbursement for inconvenience-shelter/car rental etc, thats going to be expensive. I wouldn't think premium have anything to do with the campers worth and be well unjustifiable. I understand if you lost camper tomorrow, 500 miles from home you'd be up a creek but doesn't mean someone else is going to risk covering that for a few dollars. But practical would be up to you.
Rambling-last thought is Glen-L site etc, might yeild leads, many home builts out there-
All that aside & hope you find something that'll work for you,
really curious about the camper. It looks awfully nice for a $3500
camper. If home built some one went the distance judging from pics. (the 2 teaser pics I might add:). Took me a sec to identify that funny looking floor mat, maiden trip home?