I'd suggest a piece of 3/4 ply 4x8 sheet.
Install your eyebolts to that with large washers.
Put a non slip mat (maybe that black mesh tool drawer liner stuff) down in the truck. Then put the ply down. Then ride the bike in and anchor to the eyebolts.
It shouldn't be able to tip over at that point. Center stand with a tie down to the front wheel so it can't come off.
Compress suspension with ratcheting tiedowns.
Brace the ply to the corners of the truck or to any available wall clamp points.