I don't think you can move region, only remove and repost on CL, right?
No, you cannot move a post. But why remove? Just post on more than one board. Normally, the buyer travels to the seller, but if you post in a board that's a distance from you, be prepared for some push back from a buyer on travel, which is reasonable. Someone from New Hampshire posted an ad on the Boston board, and agreed to drive down to Boston (where I am) to make the sale.
I live 4 miles from the border of the other region

I ended up removing/readding two as a trial. Their site said don't post in multiple regions, so I figured I'd play by the rules

I haven't had any more nibbles, so I'm going to probably switch strategies and put up firm prices instead of 'what everyone asks for' and wait for them to try and negotiate.