The only thing I can think of is to mimic the newer bow stops and I'm not even sure if it would work.
Could you cut about 2 inches from the middle of the post then weld plates steel plates on either side and mount the winch on the outside like the newer bow stops? I have no idea if this would work or not but it's the only thing I could come up with and I have no idea how much it would cost to do.
Any decent welder can knock out these changes in a day. I would suggest taking the whole rig to them to make a plan then splash the boat and let them work on the trailer alone. The other option would be to have them fabricate a bolt on part.
I have a Ram-Lin trailer as a loaner and agree that the turnbuckle is a PITA.
i have the same trailer and not being to fully tighten down the boat drives me up the wall, the slight bouncing action of the boat on the trailer worries the pi$$ out of me, luckily i only have to pull it about 15 miles each but still it annoys me, i was looking at it the other day and there really isn't anywhere to mount one unless it's right in the V of the trailer where the tongue goes through and even then you don't have anything to tighten it down to, the turn buckle sucks in my opinion and crash pads are ok until you get the boat so tight against them you can't put the dang cover back on