Would a piece of gutter work? It wouldn't be very deep, but it wouldn't roll on you!
DH said if you have a table/workbench you can screw the pipe into, you can stabilize it...hold the pipe in place at both ends. Then the first side cutting mark would be on the top of the pipe. Cut. Then turn the pipe to the other side of the area you want to cut and drill screws in to keep that side stable with the cutting line on the top again. Does that make sense without illustrations?
