Best adhesive w/o buying a whole new back?

So I purchased a use N6 and there was some work done it. The previous owner didn't apply any new adhesive to the battery cover so it was coming up on the sides where it lost some of the stickiness. I removed all the old foamy adhesive (took forever) and I have tried putting on Scotch double sided tape, but that was too thin, so it also came up on the sides. Now I have tried another foamy type double sided tape but it's too thick...

I really don't wanna purchase a whole new back for 12-20 bucks.. just hoping to find a cheap alternative that works as well as the stock adhesive. Any suggestions?