If you feel safe with a torch of some type, you can also heat them (maybe MAPP gas). When they are cooling, but good and warm, douse them with penetrating oil and let the heat soak it up. The expansion from heat usually helps draw it in further.
If, as
@OR VietVet stated, of you can't tackle it, or find a shop to do so, then leave well enough alone. If the shock mounts are that rusty, I would assume the remainder of important hardware underneath (fuel lines, brake lines, coolant tube, A/C lines, could all be in the same boat and a ticking time bomb that will nickel and dime you.
My rule of thumb is when a car gets that rusty, it's time to look for a replacement. I know it has low miles for the year, but that's not enough in my book to deal with rust headaches.
I remember working on an old farmers Olds 98 with about 55k on it. From the outside it looked good, but was parked on a damp shed floor it's whole life and almost broke apart when lifting it! We advised we would no longer service it and he ended up scrapping it. Not worth the risk to him or others. Just something to ponder.
