I would not worry about the dealer being close to you. I purchased my trailer from a dealer about 120 miles away and then about two months later, her went out of business.
Most companies will allow other dealers to work on your trailer if the selling one is too far away. You just have to get authorization. There are also many independent RV service shops and mobile service technicians that will/can be authorized to do warranty work.
My last two trailers have never needed to go back for any warranty work at all. Most things can be repaired or fixed easily by anyone who is even partly familiar with tools.
I did have a slide problem one time that was fixed by a mobile repairman for $75 and another time we had a water heater problem and it cost me $60 for that fix. Any other issues, and there is always seems to be some issue popping up, have been fixed by me.
Any way, I would not let the closeness of the selling dealer by a deciding factor in my purchase of a new trailer.
Good luck. :)
Barney