......tires....

gmw photos wrote:

......If the tires show no signs of degradation I would continue to use them until the first signs of a problem........snip

The problem here for the OP is this "first sign of a problem" may well be side of the road, changing a destroyed tire, with traffic zooming by a couple feet away.

To the OP, to quote Inspector Callahan, "do 'ya feel lucky punk ? Well, do ya" ?

I have two numbers and two letters for you. 16". LT.

That is all. Carry on men.

Agreed. Upgrade to 16" LT tires if your plans are to keep trailr for Taking a chance a getting a flat is no big deal. In an hour or two yo can get it changed and get going again if you're lucky.
The real risk is the damage you will do to your trailer when you have a blowout. As mentioned above blowouts will damage siding, wheel wells,propane lines etc.
OP mentions a 5K trip and a 2K trip. You do not want to be in the middle on no where when things go bad.
RV ST tires are notorious for blow outs. There are many of us who have suffered blowouts and the extensive damage that goes with it.
Do yourself a favor and upgrade to 16" E rated LT tires and rims.
Michelin ribs, Duravis or Commercial T/A's.

I have been in your shoes. I have the T shirt. My prior TT was a 39' with a 11K GVW.
I was a slow learner and suffered my share of tire problems until I upgraded. I did not heed this same advice when others tried to enlighten me. Learn from my mistakes.
The cost of the tire rim upgrade will not be cheap $1500-$2000. However it will be much cheaper than the cost of the upgrade + body damage repairs caused by blow out.
I won't get into the aggravation and inconvenience of breaking down on the road.
For the record a 8500 dry TT should have never been spec'd with 15" D rated tires!