The Stovebolt Site Forums The Shop Area Paint and Body Shop What is Good Enough for a Filler Job

I would not recommend using mineral spirits on your body work. Mineral spirits has a paraffin(petroleum)base. All of your body panels should be wiped down with an automotive wax and grease remover. You can buy it from your local automotive paint store.
For the most part, your fenders look pretty good,as you mention it is just the heel and toe that seem to have a lot of stretch in the metal. You seem to be doing a great job with the body filler. The only problem is the thick body filler on the front of the fenders will be highly susceptible to rock damage. It's not too late to weld in those heel/toe patch panels.
Keep up the good work and keep us posted.