You may want to read your policy. See if they have the right to
assign a repair shop. I know that in California it used to be illegal for an insurance company to insist on their own designated repair shops (I think it still is). They can give you a list of "
Preferred" shops but where you have the work done is your choice unless otherwise specified in your policy.
If you take it to a TM dealer, the insurance company should have to honor their estimate because it is a TM product. If you take it to a (non-TM) repair shop of your choice, they may try to argue that repair shop is over-priced because they aren't familiar with the product. It's pretty hard to make that argument with an authorized dealer.
The one disadvantage that you may have is the age of the trailer (same age as mine).
As for installing 15" tires,
absolutely.....you will
hate yourself if you don't
. It's just a matter of installing a couple frame spacers to lift the frame. I lifted mine 2.5"......I'm a little sorry that I didn't go 3" or even 3.5".
It sure is nice having that extra clearance when dumping the holding tank too.....