I am working on building a Pathfinder and I was ready to sand the rough contour of the leading and trailing edges of the horizontal stab.  I decided to do it on my workbench in the garage so I wouldn't have to clean up the mess on my building bench.  While walking down the cement steps off my back porch I had an idea.  How about just laying the paper on the steps and doing it?  After doing that for a bit with 60 grit paper I thought hey the cement finish on the steps is about 60 grit.  I proceeded to rough sand the leading and trailing edges in to the rough shape that I wanted directly on the surface of the steps without the paper.  I then put the 60 grit back down on the steps and was able to carefully flat sand the mismatch of the glue joints on the flat surfaces.  Worked great and it was fast.  It's now ready to go to 120 grit and so on to finish it up.

Now I never thought of that.  Sounds like it worked well for you!  The "finished product" looks good!

Big Bear