But if it is a concrete boat ramp don't turn while you are in 4 lo. You could do some damage on a hard top surface. Otherwise you should be fine. Towing capacity is officially 1000 lbs on the 'ole 4 gerbil engine so you should be well under that.
Brandon Sutter EMT-P
2002 Jeep Wrangler, 65,000 miles, 2" Pro-Comp Lift, 31" All-Terrains, aftermarket front and rear bumpers, tuffy overhead radio lockbox