RE: Turbulators, are they supposed to stick up from ribs or be even?
The longer the sanding block the easier the job.
Stick-on sandpaper is magic stuff. I make all manner of special sanding blocks for all manner of tasks. I had a length of hardwood scrap that does an excellent job after attaching stick-on to it. It spans about 3 bays and really helps keep me from dishing where I don't want dishing.