FYI - the best pics I ever took using the method you described are at the beginning of this thread
http://www.iceinspace.com.au/forum/a...e.php?a=200191. Might give you an idea of what's possible using an untracked (large-ish) Dob, DLSR and a lot of post.
Edit; I should add that this is using eyepiece projection, which is partly how the planets were that big in frame. EP projection isn;t really recommended because you have to deal with EP imperfections and the fact that they're generally made for displaying an image for eyes, not cameras. :-)