I always ride the bike up onto the bed of the truck using a short
ramp and tie down the front with a canyon dancer and the back with a cable lock looped through the ramp now loaded and the back wheel. Taking it off, I walk the bike down using the front brake. This is fast and easy, I have hit twisties with the truck, bike on the back at high speed, no issues.
Things to watch for are, some truck tail gate support straps are not strong enough, with a short ramp as shown the angle is too steep, so you need to find a high curb, or little hill and finally if the front fender touches, you may need to use a block of wood or something similar.
I have a Tundra, the tail gate supports are strong enough and no support needed on the front bed to support the bike weight.
If you have never done this before, it is probably best to get someone to show and help you the first time.