I've loaded in the wet several times and never had any problems. Maybe a change in your method would help... I don't power up the ramp, I use the momentum of the bike and only use a small amount of throttle if I didn't get the momentum correct. When I load in my driveway I only have 6 to 8 feet of approach...this takes a little more commitment at launch but it still serves me well.
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17 Chevy 2500 DC Long box Gasser Z71 4.10
18 Vengeance 28V