You have to get creative with your sanding blocks. I rarely use any store purchased sanding boards/blocks and tend to use things I have fabricated. My favorite is a short piece (about 4" long) of oak corner moulding. I wrap the paper around it, can hold on well and have two sanding surfaces with rounded edges. If fits in tight spaces and contours. You might try a hardwood dowel or something similar for your inside curves. The main point is you want to use something narrow with a slight curve especially on the edges so it wont dig in.
