you don’t mean true linear bearings haha I get you just mean slots to mount it.
this is a larger version 3"x4" extrusion just about fitting 63100 motors, previously was 3x3 fitting 6374.
that has truck mounting 2.5x1.625 pattern making outputs go sideways or fwd/back
Allowing you to mount some sort of additional powered mechanism to an Esk8. Perhaps a propeller for the amphibious Esk8
A suspension designed around this this with drive shafts would be something to keep in mind. Both a lean to steer and handlebar input based system could be made from that. Or also maybe something like the E-Flexboardz could be a good idea.