Trouble installing new shocks.

When I had trouble with the gas tank seal, I put it on the filler tube and let it sit in the oven at 1050° F for about 15 - 20 minutes so the rubber could expand a little with the pin in the center...

Have you thought about putting the stud in the end of the shock, then let it sit in an oven at 150° for a while to let it "loosen up"... When the rubber is warm, the molecules can creep/relax and it may help expand the inner diameter if you have the stud in there while you heat it and let it soak in heat for a while... Most rubber can take up to 250° before melting, so 150° is pretty safe as long as the shock can withstand it, and it should since temps coming off some black top roads in summer can reach those temps...

Or if you are concerned about heating the shock up, is there a way to just do the end part? Maybe a heat gun or hair drier for a while with the stud in. Can you use the stud plate stud for it?

We've also used those "torpedo" heaters in the garage and let parts sit in front of them, but you have to watch the distance because those can be very hot. I feel the oven is a more controlled heating source to prevent overheating and damaging the rubber...