Brother I have the same problem. My problem began with arm wrestling and to many isolation exercises for biceps, basically causing imbalances and excessive strain on the elbow flexors. For the last few years I haven't done any isolation for my arms except some body weight dips and close grip benches. These are basically tricep exercises but I use them for chest and not focus solely on triceps per say. My arms are still keeping up despite the fact that I don't train them in isolation. I train other body parts and try to do body weight rows, pull ups of all variations, pushups etc. To basically try and balance the imbalances. This has worked well in strengthening my arm in a functional way and in keeping the elbow at bay and soon I will start to incorporate isolation work for my arms again without over working my elbow flexors and causing extra inflamation. It also helps to strengthen your under arms with grip exercises, Obviously when tennis elbow strikes there isn't really something you can do except for some damage control, cause trying to do anything hurt like a mofo. The stuff you are suggesting is good and obviously it needs rest.
