Richard Ferguson wrote:

....snip...

Added to what Richard suggests ...

A 92_ish GMC turbo diesel V-8 aughta do nicely ...
18 to 20 mpg unloaded ... 10mpg at 70mph w/7000lbs of cargo trlr ...
but ...
=locate= a good GMC diesel tech 1st ... .

I'd opt for all_whl trlr elec brakes, a class IV recvr, & an equalizer
hitch .
The hydraulic 'assist' tends to "push" & jacknife.
'Elec' is the best on 'wet' & 'snow'.
3rd wheel( & goose neck ) is nicer, but pricy.

Its been my observation( good or bad ) that 3/4T used gassers arent
quite
a s well maintained as 3/4T used diesels.

OD use on an 'auto' is OK on the 'flat' .. with a big diesel ...
else, 'hills' ... use 3rd & slo down a bit ... 60 ???

"Toys' tend to get bigger, & more expensive,
as boys change "sizes".

Ed.