Absolutely NOT being unreasonable.
You've told him to remove it..7 months have gone by since.
Maybe, out of courtesy (not that you haven't been more than enough already) but, for YOUR peace of mind....give him ONE more notice to remove it, or it is GONE. And do not feel guilty for getting rid of it, no matter your means.

And as far as your belongings being dumped upon in garage. Hell NO, you're not unreasonable. Like you, I'd never do that to another, either, and I expect the same awareness and respect in return.
If he won't remove his crap off of yours, then....dump it elsewhere. Simple.

People like that irritate the hell our of me, too. You are not alone.
You are not unreasonable.

Shangrala