I carry a couple 2x10's and a couple 2x12's 4-5' long, with the ends cut at 45*. Plus a couple shorter boards as well. I do need to replace some boards next season due to age and cracking, and when I do so I will probably go with all 2x10's as they are plenty wide for a 225 tire. I have used 2x8's before, but they don't have much margin if the board is placed at a slight angle (wife places the board(s) once I move the trailer forward/back after checking site for level). I keep all of the tire on the board without hanging over at all.
I do need to start carrying some 1/2" treated plywood for under the high side as some sites the ground is soft enough and after the trailer sits the high side has become the low side. Seems to happen more so on our new trailer when the double slide side has started out as the high side.
If your tv is a p/u, just cut the boards so they will fit width wise at the tailgate. Stand on edge to minimize the space taken. Easy to grab (if you can lower the tailgate) once you arrive at the cg.
