short rod
If the rod length is ideal or perfect, then sitting on the level garage floor your track lugs should all have about the same pressure and the track system will be parallel with the floor.
as you shorten the rod from that ideal length the back of the track will begin to rise off the floor, weight will begin to be biased to the front of the skid................and as the back of the track comes up traction out in the snow will be diminish.
In other words, too short a rod, crappy rig going through the snow !
Best to get over tall bike and adjust for maximum traction.