I own both an Acura 2001 MDX w/heavy duty tow package, rated for 3,500 total lbs, and a 2005 Chevy Colorado 3500 rated for 4,000 total lbs.
I'd like to safely tow a 2 horse trailer, typically with only one horse.
I'd like opinions as to if you think this is possible and safe to do.
Thanks

You're cutting it pretty close on weights. A light trailer and one horse will squeeze into that weight, but you should have some "extra". I like at least 15% left of the max towing capacity with horses. I do think a Brenderup will fit the bill. They are the eaziest towing 2 horse bumper trailer I've tried. My review is at http://www.booksfast.net/qstour5.htm