First, yes, I bought a pet shaver from Walmart and shaved my cats to help them keep cool in Fla. No, it wasn't hard and didn't require restraining them, they seemed to enjoy it. I had already gotten them used to regular brushing, rough enough to remove what seemed like a woven sweater's worth of fur off of them every day, so the clipper didn't make much of an impact...for her. Sasha had no problem and was actually purring while I shaved her so I was able to do a pretty thorough job of it.
Pasha was a bigger problem, he'd sit still long enough for me to do a patch, then he'd pretend-claw and growl a bit, turn around and come back again. He only kinda like-hated it. So he was a little patchy in the end.
The problem was that after this, they seemed to no longer recognize each other. They started hissing and scratching. They went into hiding, each at one end of the boat, eyeing the other one suspiciously from under a bunch of stuff on from on top of a shelf.
I knew things were serious when they fought over the food bowl. Normally, he would stuff his face in the bowl first, gulping what he could. She would wait patiently for a chance to eat her bit, until he pushed her aside again. That was the order of things, it wasn't fair but it kept the peace. Now, they literally fought, hissed and scratched, sometimes both left the food bowl untouched and ran off to hide in their secret spots. Gradually, she came to have the upper-hand over the food bowl, actually.
Anyway, turns out this is a thing that cats do when they're shaved, bathed, taken to a vet, or otherwise separated for a while: they forget each other's scent. Cats are not known for their loyalty.
It took about a week before things were back to semi-normal.
Anyway, after a month, they were pretty much all done with all that. They took turns sitting on my lap on the long slow drive back up to NYC. The process of introducing the cats to the boat was going to go slow.