Why not just slide the tubes farther up into the tree? As a rider with short legs I needed a way to lower the seat height. I have moved the forks up by as much as 2" on my F-2's with little problem, I don't remember any interference issues and didn't find the slightly steeper steering head angle an issue. Another way to 'shorten' up the forks was to put spacers in them, we did this on dragbikes but you may find the spring preload excessive. I've ridden with both of these methods. For my raked custom the spacered version didn't let the frame sag so much but was harsh.