If you can't find a CFII willing to do the initial instrument training in your airplane, I guess you're left with getting the rating in whatever airplane your chosen flight school uses for an instrument trainer.
If that airplane happens to be equipped with analog instruments, that isn't all bad. Learning to maintain situational awareness with steam gauges is harder than when a graphic picture is provided for you by a glass panel. In my opinion, learning with analog instruments tends to make a better instrument pilot, much like taking primary flight training in a tailwheel airplane tends to make a better "stick" than those trained in a tricycle gear airplane. However, there is an argument to be made to seek initial instrument training in an airplane with a glass cockpit. If you learn on steam gauges, additional training with the operation of electronic flight systems would be required. More time and money spent! [As an airplane owner, you should be used to that by now.]
Either way, you will end up training in an airplane with a glass cockpit. If you have to do this in another airplane, it would be to your advantage if that airplane had the same EFS as your Cub. If not the same model of equipment, at least the EFS should be from the same manufacturer in order for the menu architecture to be the same.
I think you will enjoy getting the instrument rating. From your point of view, the rating will allow extra utility from your airplane. It will certainly do that, but you will also find that the training will make all of your flying much more precise.