So peter.c and Nealh, I took the plunge and ordered the kit from Woosh, it came today, my LBS pulled the BB today, and I installed it today - oh my, it's insanely good. I've never ridden an e-bike before, but it was magical. I was doing 15 mph up an annoying hill right by my house, around 5% grade, pedaling an enjoyable amount but not dying like I usually do. It didn't really feel like there was a ton of assistance, it just felt like I was Lance Armstrong or something. Wonderful experience, would recommend.
Pics attached, and very related.
The issues I had while installing:
- As expected, the cable guide would not fit with the motor on there. I yanked the cable guide off, pulled the front derailleur off entirely, then asked the LBS for advice on rerouting the rear cable. They cable tied a bit of outer sheath between the motor and frame, and that seems to work well - not sure on longevity, but cross that bridge when we get there.
- The small remote controller wouldn't fit around my handlebars, so I'm going without for now. I'll find a solution that will almost certainly involve more zipties, but for now, the screen itself works well enough.
- The battery _nearly_ didn't fit on my downtube where the current rivnuts were, but fits fine now with the front derailleur removed.
- The rear beams going from the bottom bracket to the rear wheel were nearly too thick for the brace plate bolt thing, but managed to get it on and tight-ish. I think it has enough thread bite.
- There wasn't enough clearance between the speed sensor and the spokes of the rear wheel, so the Woosh kit recommended removing the mount bracket and just cable tying it on - this worked, though it is still pretty close.
- I need to waterproof the battery connectors, as it doesn't look like those connectors are going to be waterproof.
- It was extremely sunny out while I was doing the install, and now I am sunburnt.

I've attached pics of the cable tie sheathing between the motor and the bracket as well as the connectors, and the finished bike!