replacement trailer bunks material

[bigeasy1]

I'm still tinkering around with the trailer(Roller Trailer) that my Tsunami sits on.Loading the boat is a nightmare.So anyway I'm going to add a couple bunks that will line up on the inner step on the outside panel of the hull.
My thinking is the the bunks will act as a guide and will keep the hull from listing(severe tilt) to port like it does now.
We've tried everything to no avail,sometimes we get lucky and it sits perfectly level,but most time we have to make 4 to 5 tries to get it to load correctly with no tilt,and sit right.

Any thoughts on Material? I've seen everything from standard fir ,cypress,pressure treated,etc. I hear good and bad on all of them
I was thinking of using some Trex 5/4 decking for the bunks,and maybe adding some strips of polyethylene or lexan to make the surface a bit more slippery,or is carpet a better choice.

Any thoughts are welcomed.