Okay, I'll venture some heresy here.
I am 5 1/2 months out on a 10000 mile tour from Miami to Seattle and back. I am towing a 31'
Sovereign that was weighed last at 7800#.
I am towing it with a 2004 Nissan Titan.
Okay -- I can't run all day at 75 because my tires are rated for 65 and my wallet is calibrated for 55 (at 55 I get 13-14 mpg vice 10-11 at 65)
On probably half a dozen climbs (i.e Stevens Pass in Wyomimg) I had to motor on up at 45 in the granny lane using 3rd gear. Probably a total of 45 minutes of climbing at that speed. Descents, again in 3rd, no problem.
While I was shopping, the best deal I could get on a 3/4 ton with a diesel was a solid $8 grand more than my Titan.
I am very happy with my Titan although my brother-in-law has the new Tundra and it very nice -- probably next time....
mike the heretic