You generally want to test
You generally want to test waters with simpler parts, power board or something. The thing with camera sensors is they can't handle heat, if you didn't specify to manufacturer that sensor must be soldered manually they probably stuck it in the oven and cooked it.
Also these manufacturer do tons of designs from tons of companies and have huge amount of experience about it, if they complain its generally for a good reason and it pays to listen and fix the design. Its in their interests for the boards to turn out OK so you would come back for more, so if they complain they fear things are not going to work as intended and you won't be happy with the end result. The companies that don't complain are the type that don't give a fig about the end result, they will take your money and your design and it will turn out however it will turn out, usually for the worse.
