Here's what I did:
I dremeled the opening on my bumper case.
This was not perfectly satisfying because--
-There didn't seem to be a way to enlarge the opening without removing the thin, flat portion of plastic that is flush to the metal bottom of the phone;
-I overdid it a bit on one edge and removed too much plastic, and slightly compromised the structural integrity of the case;
-It looks rough.
The non- Apple bumper alternatives that I've looked at fall short for one reason or another.
I recently purchased (off eBay) an "EOM" chinese copy of the Apple bumper, and I might experiment with that.
Another approach would be a dock extender, such as Sendstation (however, their current model does NOT fit the Apple bumper. They are supposedly in the process of making a smaller model). There is a dock extender available at GadgetBoost for $19 that supposedly fits any iphone/ipod/ipad case/dock combination.
And, of course, y'can always take the dremel to your LOD connector, as you propose.