You might be tempted take out @4mm worth of washers, readjust the cone if need be, and retighten the locknut really good. Pay attention to chainline, as you've just moved your biggest cog inboard a few mils. keep the spacers around, in case you end up deeming this to be a failure. You'll likely need to redish your wheel. Reading Sheldon's sight, he's saing you need to redish and respace the frame to accept the 130mm. As you and Jeff have suggested, there must be an easier way.

Sheldon suggests:

an easier way: Try this. Buy one of these: http://www.jensonusa.com/store/produ...ehub+Body.aspx
Install it. Buy a 9 speed cassette. Make sure it has easily removable cogs. Ditch the 9th cog. You may or may not need the "extra" spacer; sheldon doesn't say. You now have 8 speeds on a HG body, and you've retained your 126mm spacing. You will need 9speed chain, and you'll need either friction shifting in the rear, or a 9speed shifter. Don't forget to tweak your limit screws if need be. (Check first, though; you might not need to.)

hth,
-rob

ps-the 7speed stx freehub body probably won't accept an 11t small cog. might be better to get a road cassette with something like a 12/27 or 12/26...