I had an RZR on a 5000 lb. If I remember you have a new Supra SA, I'm guessing your going to need bigger than 5000. RZR has a listed weight of 3200 and a tested weight of 4000+ lbs in lake form. Whats the Supra weigh? Probably need to add 5-600 lbs minimum for lake form. Better yet run it across a scale.
We have a Walks on Water brand. They were right at $5K with aluminum inboard bunks(24 inch legs) thats just base lift. Canopy is like $1900 more, wheel kit is $500 for 2 wheels, side boards are close to $500 and electric winch is $800(110v no remote)-$1400(24V solar charger with remote). They get expensive fast. From what we saw they(this brand) are on the inexpensive side. You can easily spend way more on a Floe, Beach King, Shoremaster..etc.