I had the same issue with my boat. I got four stands, two that are more often seen supporting power boats. I was able to position those two stands under the hull aft, where the hull form is fairly flat. I then screwed the pads up to raise the stern a bit. Then I took a ten foot 3x5 timber and placed it thwartships under the bow. Inside the forward end of the trailer I used an over-sized bottle jack with a 'V' block cut out of wood. I got the bottle jack, 20 ton, for $30 at the local discount tool store. I bought it oversize just for stability purposes. I used the bottle jack to raise the bow. After I'd raised it about a foot, I placed concrete blocks on either side of the trailer, with the 3x5 resting on them. I then lowered the boat down on to the 3x5 and blocked up my jack for the next lift up. I think I ended up with the cement blocks four high on each side. I adjusted the rear jacks as I raised the boat. Once I got the bow up to the fourth block height, that was sufficient for my trailer's fenders to clear the 3x5, and I pulled the trailer out. I continued jacking until I got to the height where I could get my forward boat stands under the bows. I then raised it further with all four boat stands.
The 3x5 was handy because sometimes I needed the 3" height, and sometimes the 5" height, while jacking up the bow.
I was seconds away from getting the final paint stripped from the hull, and the new bottom paint on, when winter returned with a vengence. With my luck, someone will make an offer on my 'for-sale' house and I'll have to lower it back on to the trailer, transport it, and repeat the procedure before i get it painted.(g)
I hope you have an older barn. I could envision some fun if you have pre-fab joists.
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.