I've pushed the B string over the side of the neck a couple of times, but it doesn't seem to happen that often. The flats sound like a good idea - I might go for a set of them when it needs a re-string.
I've got some leave to use up next week, so the plan is to treat myself to a studio day, setting up my pedal board properly and giving the full rig a decent workout. I'm dead keen to hear what it sounds like, too. I'm hoping to get a really full-on, rattle-the-windows, loosen-your-fillings sound. Like you, I don't look for much in the treble range - full warm mids and a deep dirty low end are where it's at for me.
If it sounds OK and I can record it at a decent quality, I'll risk the laughter of da BC massif and post a video. Watch this space!