Steve, welcome!
Yes the trunk is a surprise to all new e34 owners, and old ones that lack an overly adventourous spirit! I remember thinking that secret compartment under the carpet was a great place to hide an an automatic assault rifle on the odd sojourn to or from East Germany. Where I live there is no need to run arms accross the border...Nick
BTW; Have you found the correct mounting point for the newly found jack (up high in the RH quarter panel)? Did you find it in the under the floor in 'the e34's secret armoury' as mentioned above?