Too bad about the condition of that trailer - probably a good move to pass on it with the water damage, though.
If you want info on various HiLo models, there's a page on HiLo's web site (
https://www.hilotrailer.com/home/then) that has PDF copies of factory brochures from the 1960's through the end of production in 2010 - very helpful if you're looking for specifications or trying to compare models.
We bought a 2nd owner 50th Anniversary 2307C (2007 23' Classic) about 2 years ago after owning everything from Coleman pop-up tent trailers to a vintage 26' Airstream - other than the little tent trailers, the HiLo is easiest towing trailer I've ever owned.
We tow with a 2002 GMC Sierra 1500 - 5.3 V8, automatic transmission, short bed, extended cab, factory tow package (listed towing capacity is 8000 lbs; hitch capacity with a weight distributing hitch is 12000 lbs / 1200 lbs tongue weight, 6000 lbs & 600 lbs tongue weight without).
Dry weight for the 2307C is 4023 lbs (3475 lbs axle, 550 lbs tongue) - we use a weight distributing hitch and a pair of Air Lift air springs on the rear axle (aired up to about 70 psi) to firm up the rear suspension when towing. We've had zero issues in multiple trips - on level ground we average around 14-15 MPG at a steady 60 MPH, and when traffic is light it's all too easy to creep up to 70 or more.