I'd do it and not even think about it... with 3.55 or 3.73 gears ONLY... 3.31 and there is no way.
The truck and chassis can handle it just fine.
Driving a 4.6 every day myself... it had good TQ...just let it rev and it will get there...
Just think that little 4.6 has more HP than big blocks that towed monster fivers 30 years ago.
Make sure you have a WD hitch, proper receiver, transmission cooler, and especially, the gears. Your towing... not racing.. let it rev... it's really okay to go slower and take in the scenery.
thanks!
Jeremaih