We just bought a R25sc and tow it with a GMC 2500HD, 6.6L diesel, 4x4, Allison 6 speed transmission, trailer package, limited-slip diff - the works. I upgraded the hitch to a Commercial Duty model rated at 18,000 Lbs; and had installed a trailer-brake controller for the trailer's electric-over-hydraulic brakes.
The truck's Gross Combined Weight Rating (total truck/boat/trailer package) is 22,000 Lbs.
The truck is listed as weighing 9200 Lbs (empty).
The boat is about 6200 Lbs (empty) plus 1800 Lbs for the trailer equals 8000 Lbs. Add in some water, fuel and gear and it quickly approaches 10,000 Lbs (I'm estimating here - I haven't been to the scales yet).
That leaves me about 2000 Lbs margin for people, truck fuel, etc. That margin can quickly get used up if I'm not careful.
Now check the capacities of your 1500 (I'm guessing much lower) and add in the extra weight of the R27 over our R25; and I think you will quickly determine that the 1500 is not adequate.
Learn the numbers and do the math, then err on the higher side for safety.