Finally, I've managed to put it all together!  Bolting the cockpit onto the frame was a bit of a challenge (read painful!), but attaching it to the base was surprisingly simple.  Seeing as the hydraulics are conspicuous by their absence, I'm going to build a simple locking frame that will ensure it doesn't move when I get in.  Next on the agenda is testing, which is going to involve looking at angles and forces.  I can hardly wait...  :P