Since you have considered all the other options, here is another way that may work for you with some thought.... if you are on good concrete and with good std construction scaffold and good rollers and with an extra level mounted above the work floor, you may be able to solidly mount a heavy drill to a frame which can then be secured to the upper scaffold frame with nylon ratchet straps or clamps and adjusted for height. Then just use a couple more ratchet straps to go around the angle (I assume there is 1/4" min clear) and just pull the scaffold forward. I suggest you sweep the roller track on the floor first.
alternatively if the rolling surface is poor... Fab the frame so it is vertically adjustable and allow it to slide on the leveled scaffold floor.
Do what it takes to complete the job safely. Good luck.