Does your ZJ have a tranny cooler? If not, you could add one. That would help keep it cool. Also, make sure you are running brakes on the boat trailer and you should be OK. You may need to beef up the rear shocks or replace them with adjustable shocks to support the tongue weight.
2000 Jeep Grand Cherokee V8 Stock
93 YJ I6 hard top (really belongs to SPEED)
RE 4.5" Extreme Duty Lift, Advanced Adapters SYE, Tom Woods CV Drive Shaft, EA589 10" rims with 33" x 12.5" MT/Rs
Bullet Proof Front and Rear Bumpers and Tow bar