Frank,
Slow and steady loading with very strong ramps, chocked tires, if needed, and truck in gear with parking brake.
I use good judgment. I don't let anyone else load it. Why would I trust general laborers?
You can raise your dump bed a bit to make the tail a bit lower. I never do. I definitely will load downhill if given the chance.
Avoid the crown of the road.
Shim your ramp foot if needed.
Slow, Smooth and Steady and you're in.
You climb and rig trees for a living, you can load the truck. For a bit over a $1000, you own ramps that will also bridge gaps, perhaps offload the mini above a rotten railroad tie retaining wall allowing access that is otherwise impossibly, as I did.
I would like a side-load with easy, flip-down ramps. But you can't go too high without some more serious engineering. I move the ramps between my 2 trucks, and can use them on a trailer. I don't regret buying them one bit.
If the mini-on chipper fits your niche, don't let me discourage you. If its about loading a truck, it a skilled manuever.