That looks great! I never saw your first question on insulation. It looks like you've done a great job with the Thinsulate. Do you want to keep the E-track? If so I would leave it and attach wall panels to the ribs above and below it. It not just yank the E-track and mount your paneling directly to the ribs for solid walls. You want a little air space between insulation and walls. Moisture should not get there. It can but it shouldn't.
If your floor plan requires every possible inch of space side to side, say for a lateral bed or something, then you may want to rip out the whole works and mount wall panels directly to the van's inner structure. Me, I'd mount to that structure that's already there.