Upon reading your post, I'm afraid that I may have forgotten more than I've learned about the roller process. I've read 90% of the threads 4-5 times and it's amazing how many great ideas will slip your mind each time... stuff that you don't think applies to you so you skim past it.

I have an 8" wide curved panel that runs the entire length of my truck, just above the upper moulding. Since hand-sanding is useless with ripples and the rubber block won't conform to the panel, your foam pad may be perfect for me regardless of which technique I use.

I'm sure glad my truck has plenty of straight, but junk panels. On my most recent test panels, I've learned that I may not have been working the surface long enough with the roller. At 25-30% mixture, I'm getting close to 10 minutes of work time in the sun(85 degrees). The bubbles are gone, orange peel is minimal so we'll see how it levels out. If this works, my tipping brush may be headed for the trash can... this is good!