Not much difference between the 2 as far as racking the slide goes, maybe a bit easier with the 22 but not much. Can you switch hands, hold the gun in your left hand and rack it with your right?
Best bet would be to find one in a shop and give it a try. I have problems with both my hands (car wreck and using them as hammers, vises, etc all my life) but not severe enough to keep from racking a slide.
I also have a GSG Firefly (ex Sig Mosquito) and a M1911, both 22s. The Firefly is easier to rack but it's a bit bigger than the Bersa Thunder 22. Just have to use high velocity ammo (I use Fiocchi in all my guns). Here's the Firefly:
Has a slide safety and a decocker lever, holds 10+1. Feels nice in the hand too.