I' don't know why your BFG's didn't last.

I've got a pair on the back of my 87 F250 2wd truck( stock size 235/85/16 load range E ). They have over 50,000 miles on them and they are still around 70% tread. They've outlasted a couple of my trucks!

I've had these for 6 or 7 years and they have been on a 1 ton van and three different F250's.
I haul scrap metal so there has been plenty of heavy loads on them.
If throwing rocks and paint chips are an issue I have a couple suggestions. Can you say fender flairs and mud flaps!

They are an aggressive tire so they will kick up stuff.
When I get the cash my F-Super Duty is getting a whole set of them!
I buy mine from tirerack.com and then have a local shop mount them. It's saves some cash over paying the mark up at the tire dealers.