Pretty accepted good idea not to tow from your bumper regardless what it is rated for. Bumper ratings are misleading. The bumper may be rated for 5500 but are the bolts holding the bumper on? Too many horror stories about bumpers coming loose (LaMoy) and hitch balls bending and ripping out. Get a frame mounted hitch system. They distribute the weight of your toungue better, give you better control, stoping and turning radius as well as peace of mind. If you were towing a flat bottom john...then maybe but you invested a lot in your boat, don't scrimp on the hitch.
As for an explorer towing, go look in my library, I pull a 929 with mine and it does fine (until you get in the mountains, then it strains!!). V8, Tow package, tranney cooler, and offroad suspension help. BTW, I was born and raised in Omaha where you gonna fish with that new rig?
TOXIC