Best way to extend my rig

[theoptimisticcynic]

Hello, I am in the process of adding motion to my Simlab TR1 rig using essentially SFX-100 actuators. I'm using different motors and will provide a build log shortly but I'm the mean time I'm trying to solve an issue. Unfortunately due to the compact nature of the TR1 design there isn't enough clearance at the front or back to attach the actuators. I'm thinking of just extending the rig by about 8 in in the front and 10 in in the back to make it work. I don't really want to replace the existing extrusions so was thinking of butt joining extensions with flat plate 8 hole. I'm concerned that won't be rigid enough or might be a weak spot. Alternatively I could overlap small extensions with holes drilled through the side for mounting. Of course I could also just buy new side rails but I have been trying to avoid that.

Any suggestions or experience with this scenario is appreciated.