Jerry
You have to learn how to get close enough. There is no easy way around it.
Trying to solve this problem with longer lenses is the same as trying to solve birding problems with more magnification. You have 8x binos so swap them for 10x because some detail and image size is always out of reach, but even with the 10x there are still subjects that are too small, so you go to 15x binos, then scopes, but always there is a bird out of reach.
With butterflies and dragonflies it is similar. Go for a longer lens and you will not be hand-holding it so you will need a monopod at least. I use a monopod sometimes but actually the IS of the 100mm is good enough most of the time and you can boost ISO to give extra speed or depth of field.
Go for the longer lens and two other problems arise. First, vegetation gets in the way even more than it does with the 100mm, and second, even with an unobstructed view, the further away you are the less you are looking down on the dorsal surface and the more you are looking edge-on to the butterfly, so you can't get a decent view of the upper surface. Well, you might say this can help get pics of the undersurface of blues and fritillaries but crouch down a bit to do this and there is even more vegetation in the way.
Sorry, Jerry there is no quick fix, and the only way is to learn how to stalk closer.
Lee