I agree with what was posted above. My guess is that if you pull full of water you will easily exceed 800lbs on the tongue with a trailer of that size. My 19' Lance is around 550 lbs on the tongue and 3500lbs on the single axle.
My recommendation is to have the RS dealer install the weight distribution, but then take it to a truck scale on the side of the road with the trailer and truck loaded as if you were going camping and adjust accordingly. From my experience, the dealers suck at setting these things up. I use a Reese weight distribution with my trailer and it works well. If you have a similar setup, make sure the sealer does torque the bolts that angle the ball too tight where you can't adjust them. The don't need to be torqued to 450lbs+, or if you want them that way, take it back after you adjust.
