Trailer for 20SF

[Yz2009]

ive got a 87' 20'SF with a yamaha f115 on the back. The trailer I have is in need of being rebuilt. It's currently dual axle (it was for my older 23' boat) but I'm thinking about going to a single 3500# torsion axle. From what I've seen the hull dry weight is roughly 1750# so I'm thinking the single 3500# axle will do. Anyone have input?

This will never be used on the highway. Only back roads to and from dock (about 5 miles). The boat is on a mooring all summer so the trailer will only be used 2-4 times a year.