A couple of thoughts;
I'm not sure from reading your question what kinds of bends you have in your rim, if they are short or long.
There is a type of plier type tool with wide jaws for straightening out the sides of rims. I don't know if you'd think it was worth the money to buy a set of those for just this situation. An LBS might have some and they might loan them to you or do the straightening for you reasonably.
Something I have done which is probably not politically correct (in the mechanical sense), I have a small anvil and the flat end of it is thin enough to fit into the spoke valley or gorge of most rims. With the rim slipped over that flat end I have GENTLY pounded out some dents using either a rubber or rawhide mallet. Some type of mallet with a firm but not metal face so it won't mar the rim. A piece of sheet steel C-clamped to a bench would work the same.
Don't know if this will help or not.
Good luck!