Not going to fit in the back, if the Golf/Rabbit platform is any indication.
The R32 has a completely different spare tire area compared to a GTI/Rabbit. R32 has a smaller spare and shallower tire area, so there's actually less cargo room in an R32's hatch.
This is all done in order to push the floor up higher, so the more complex rear end + Haldex + split gas tank can fit.
If the Jetta TDI is at all like the Golf in this respect, you're going to run into problems when you try to bolt it all up.
All of this aside - I love your project page linked in your sig. The wiring pinouts for the compass module will be helpful as I want to add one to my MkV R32 which supposedly doesn't have the harness plug in the headliner where it belongs on a Golf...