I made my own brackets to run 12's a few years back (rip 4runner), can be seen here: Ripcord's 2002 Sport Ed. Version 2.0 - Page 47 - Toyota 4Runner Forum - Largest 4Runner Forum

The travel, ride, and flex was pretty amazing but yes you will need large offset wheels or wheel spacers to clear them. Notice the tire rubbing marks on the shocks in this photo.







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That being said, I also designed a custom-length set of the King 4Runner kit rear shocks for @derpiful and the length is prettymuch the max you can get out of the factory rear shock location. They also flex like a mofo and don't require any fab work.

Custom Length was: 9.55" stroke, 24.75 extended, 15.20" compressed.

I would highly recommend this setup for your purposes, custom length adds about $100-200 to the cost of the pair if I remember right.