Danny,
Not being familiar with kit and thus the wheel wells I googled it and found a suitable picture.
There is a few issues you need to decide on prior to removal of the wheel well, and that's the lip that will be created on the inside of the bottom of wing, and if you need it level with the rest of the inner surface, or can live with it being beveled. My guess is level, then sand for a more scale effect.
Since you don't want to use a Dremel, I'd start off with a hand drill and the largest bit you have. Drill holes all around the bottom of the well, then cut the plastic from one hole to the next and the bottom will drop out. I'd also drill holes in the sides the best I can then cut out sections of the side walls. What's left needs to be cut off little by little leaving a slight lip. then a hobby chisel so that you can remove the remaining wheel side walls while leaving the inner wing surface level.
Joel