Did my first oil change with the Rumbux bars in place yesterday. A 13mm combo wrench and 5mm allen socket worked well to remove the 6 bolts that hold the skid plate on. The two drain plugs are still easy to access, but the crash bar is there, so you have to reach under it, then up to get your fingers on the drain plugs. No big deal, just slightly awkward with the side stand down too, on the rear one. No issues with anything and didn't add any significant time to the oil change. Easy on and off w/o any fuss.
I did notice that you don't have access for a socket wrench on the nuts, as there is not enough clearance between the exhaust pipes and the skid plate to fit the wrench in there. The front upper ones can be done with a rachet/socket, not the front lower on the right, and not the rear. In the rear, you can easily use the box end of the combo wrench, but in front the bars are close enough to the nuts that the open end works better.