Can you do it? Yes.
Should you do it? NO!
Let me count the ways..............
Frame not made to have those stresses on it. Towing/tuning/pulling. Besides you will have to go the the frame rails as the bumper is aluminum so the hitch cannot be mounted there. Additional reinforcement means more weight at the end of the frame. This can cause frame seperation.
If you are pulling a 27 foot or over, the up and down motion going over humps in the road, or in and out of driveways will throw the four wheeler off a trailer due to the lever action from the tounge dropping as your bumper drops. This will also create additional stress on the frame.
The boat is a lighter weight tounge, but even a rear bumper mounted spare tire or rack of bikes can cause frame damage.
Also, does your state even allow the 2 trailer setup? Some states do not.
Boat on the roof of the Tahoe via a roof rack, with the motor in the back of the truck. If it is a bass boat, this will not work unless you get a special rack built. 4wheelers, I would say it is time to get a truck so the 4 wheelers can go in the bed. This truck could also take the boa on a roof rack allowing you to have it all as long as you have enough truck.