Trick I learned when working on aircooled Beetle rear hubs.
Get correct socket/wrench/spanner (one in the toolkit will work fine.)
Find a pipe that fits on toolkit wrench, measure 1,2,3,4ft or whatever. (piece of conduit,flatten end with a hammer)
Stand on bathroom scale, press down until your 70lbs lighter with 1 ft bar, 35lbs with 2 ft, etc
seems to work OK on limited access axle nuts with higher torque values (40ft/lbs+)
PJ