Which one would you get mainly for remote backpack hunting but also the occasional hunt that doesn't involve as much hiking (i.e. Pronghorn)?

It's about a 10 oz step up from the 65mm to the 85mm (both with 25-60x zoom). It's about another 10 oz step up from the 85mm to the 95mm (or ~21 oz more than the 65mm). The 95mm has a 30-70x zoom.

I've only used an older Leica20x60x77 Televid and a newer Vortex (which I returned after conducting a comparison test).

Thank you.

if you want to do some digiscoping, and possibly some video, the 85mm is probably the best compromise between weight and optical performance. if keeping weight to a minimum is the priority, then take a look at the Kowa TSN-550 series of spotters; 90% (maybe 95%, they are very, very good) of the optical performance at less than half the weight.

We sell a fair amount of these system scopes and most do an initial purchase with the 65mm tube and later on add the 95mm tube.
Please feel free to give us a call to discuss what would be best for you

Pretty much what I've seen too.