I had the SportRack setup mounted on our 1007. There are two cross rails mounted directly above the roof stiffeners aft of the trailer center (weight is aft of the axle). Four channel tracks hold the wheels, with an "A" brace that clamps to the frame of the bikes.
There are four holes into the roof right at the edge moldings. These were well sealed when installed and did not leak in 7 years of use, but like all holes in your roof, there is always an added risk.
They are not a heck of a lot easier to use than the roof mount on a vehicle. Access to the two outer racks was fine, but it is still a very long reach to the tiedowns and clamp on the two centre units. We keep a small two-step stool for this.
Also, the street side rail was hard to position in such a way that it did not interfere with the aft roof vent. We did have one trip where we could not open more than a quarter inch because I forgot to make room (and I wasn't dropping the top to fix
The Sport Rack itself works, but the quality is not up to that of our other racking which is all Thule. Paint faded badly in the sun, and the plastic parts started to crack and degrade after a couple of years (carpe ductum).
IMO, considering your physical limitations, the tongue mount or a bumper system may make more sense.
For our new TT which is a hybrid, my roof option is gone. I am going with a bumper hitch mount, but have found on YouTube a good workaround to the main issue. As long as you are within the weight capacity of your bumper (most are around 200 lbs, should be in your manual) this should be workable. The problem with hitch mounts is not the weight, it is the levering effect that the rack places on the bumper, eventually twisting the bumper right off. The workaround is to weld or bolt through a couple of tiedown points on the frame rails near the back of the TT. Then run a tiedown strap from the top of the rack back to the frame rails and cinch tight. This should greatly reduce the levering effect from the rack setup. I think this would work well on the 1007, but the hitch mount would have to mounted slightly to one side to clear the spare tire mount. The way the camper base angles in at the back should give a pretty good angle for the tie downs.
ETA: just noticed in the picture below that all bikes are pointing forward. Later learned that you get better clearance by alternating the bikes forward and back, same as you would on a hitch carrier.