Thanks for linking that mod. Unfortunately I don't think that there's anything that I can use from there, as it takes a completely different approach to me. That mod just redoes the graphics for all things character-related, whereas I just try to use the existing spidertron entity (with all of its weird and wonderful features) and try to pretend that the player character does not exist inside of it :) I think that it would be quite hard to pretend that the spidertron does not exist instead.
That said, I have had a few thoughts about approaching it a different way and avoiding the spidertron GUI entirely by managing a hybrid-entity between the player (which manages all the controls and GUI but is invisible) and the spidertron which would be visibly moving around. Even if that is possible, I don't think that I would be willing to try it any time soon, it would be a complete redesign and rewrite.
I'll continue to investigate hacky ways of better integrating the 2 inline with what I am currently doing :)