[throwaway892238]

geared hub motors are a start, but it's hard to find ones with large enough gearing for the torque of a load going up a steep incline (not to mention roots, mud, etc). a few companies sell powered wheelbarrow geared hubs with much higher internal gear ratios. but i need to figure out what the maximum force required is for a given load at a given grade and then figure out how to determine if a motor can provide that; and whether a custom drivetrain will be needed or if i can cannibalize a bike or other drivetrain (and how to tell if it's capable of handling the load). like someone else mentioned, i didn't think about adding the weight of the vehicle into the calculations

[theodric]

What I suggested is a mid-drive motor, not a geared hub motor. Can then size the drive and driven sprockets to whatever reduction meets the requirements of the build.