You need a diaphram type pump that can run dry and will self prime and that will work. OR get a small tank on the truck and run a small vacuum set up. small 110volt gast pump with a converter off the truck battery. Find a dairy supply and get a lead on used step saver hose its bullet proof and will take the vacuum. Then put a ball valve and a 20" copper pipe and between trees shut the vacuum down and when you get to a bucket insert and Kattie bar the doors. Just like your local septic service but a smaller set up.