I usually ride them up. I use a tri-fold ATV ramp that is nearly as wide as the tailgate. It is a bit short though so I have to put the back wheels of the pickup in the gutter to lessen the height. I tried the whole wood plank thing and it was probably the scariest thing I've ever done so I'll stick with my big wide ramp.
2012 Yamaha Super Tenere, 1997 Honda XR650L, 1985 Honda XR350R, 1976 Honda GL1000 Goldwing