Re: bunk replacement
i use untreated pine, 2x4 or 2x6. 3 coats of a sealing paint. then carpet using galvanized roofing nails. home depot usually has some 5x8 carpets for $15. i but them, and cut length wise. this way i can get 3 trailers out of one rug.
Getting Boat Off Trailer
you don't need stands.
1/you can lower the tongue to the ground. i would get some 6x6 or old railroad crossties cut the +- 12 inches, now block up the transom. 2/
Raise the tongue of the trailer the back of trailer will drop away from trailer. this is the tricky part. between the cross braces of the trailer block the keel lower trailer, boat will be suspended on the blocks.
3/ pull forward, lift bow again, and reblock i a different place. repeat until trailer is out from under the boat.
4/ to reload, just reverse the procedure.
if you were just working on the bunks, or painting the bottom. you could just do the first 2 steps.