I'm not overly familiar with Eddies style of quarter guard, so I'm interested to hear from someone more experienced with the 10th Planet quarter guard! I have studied a lot of Lucas Leite's game though and he will do a few things to prevent the backstep...
Firstly the grips: underhooking the far leg, rather than the body
https://www.youtube.com/watch?v=HA5mltcbQv0
Pulling the opponents weight forward and/or knee bumping them forward. Note the raised shin left lagging after the knee bump right up until Leite swings it back down creating momentum to transition to dogfight.
This raised shin means if they backstep at best you can take the back/truck/rear clinch. Usually Leite can threaten the crab ride and potentially create a scramble to the back or at least recover half or reset to seated guard.
https://www.youtube.com/watch?v=fCFlGkdKxaY