I experimented some with that trimmer and was afraid of doing just what you did, so I took the plunge and bought a router (rather than continuing to borrow my neighbor's). It's come in handy for some other things, and is fun to learn how to use and the things it can do.
Early in his Cornwall thread, Marshall walks through his process for the patch. Granted, his patch was to the substrate, but it may provide some ideas. Other than that, I do not have enough experience.
I'm afraid I don't have enough experience finishing to provide any more than general advice. There are so many variables, so continue to take your time and practice to find what you are looking for. Regarding your concern that stain might make the finish too dark - you can control the darkness or depth to a great extent with the amout of time you leave each wipe on the surface before wiping off. Many short intervals will allow you to slowly build it to what you desire. Remember this, once you've finished staining, it does little good to go back later and add more, once it dries, the pores of the wood won't accept more stain. So if you decide to stain, set aside plenty of time for howver many coats/cycles of the wipe-on/wipe-off process may be needed.
Randy