I finished the work today - almost. Only need to finish the aft fixation of the jumpseat as shown on the pictures. To get the seat mounted I needed to cut of around 20 inches of the aft legroom heating tubes to get the gimbal tunnel more narrow to fit the seat.
Armrest have to be disassembled from the bucket seats otherwise there is no room for the jumpseat.
The aft fixation can not be done by drilling a hole in the floor. On the left side you have the fuel tank directly below, and on the right side you have a heatshield welded to the bottom of the car. I will fix it by welding one or two nuts directly on the floor from the inside. Before welding a hole should be drilled allowing the bolt to get half an inch through the floor.
Last thing to be done is to mount a safetybelt on the jumpseat.
My Tahoe is fitted without backseats due to hight taxes in Denmark. So right now I have got room for 3 in the Tahoe
Pictures from todays work attached.