Loading up 5th in the h55f isn't a good idea, mainly for the gearbox (no so much the engine) the reason is fifth is just tacked onto the back of the box, and isn't properly supported bearing wise. when you load it up it twists about and will damage it. (this is why alot of boxes have problems with falling out of 5th while decelerating)
also the original post says 2H motor, which is diesel. I don't know about canadia, but in aus 4.11's came standard in them (if not all). It should tow fine, even with 33's. just keep the motor above 2000rpm It will slow down a fair bit on a decent hill though, just get back a gear before you hit the hill.
In my experience, the 60 will pull 2.2k pounds without any dramas once you start getting up to the 4k mark is when it slows down. How much does a horse weight anywaY?