Been neglecting this forum, but it sounds like y'all are on the right path anyways. But yeah, it's a nice way to get a batch going to split off 3 or 5 gallons after you run off the wort, get it up to 170F or so, and then chill to 100 and add your goodbelly. The lab cultures are nice and all, but goodbelly is just way too convenient.
Regarding brett pale ales, go the 100% brett route and it won't take much longer than a sacch fermentation. Lag phase is a bit longer, but you can be bottling or kegging in around a month if you start with a healthy pitch of yeast. Just watch the IBU, as brett can make a beer pretty tart and is usually a bit phenolic, neither of which go great with bitterness. I'm not a fan of the brett strains that make your beer smell like a goat's arse, but Bootleg Biology has a couple strains that are pretty friggin' incredible.