I think I’d prefer to discuss build details in my actual build thread, but here goes… 
I am using Metr Pro CAN + separately bought MRo M9N GPS for logging. Unfortunately Metr is currently discontinued, and the original creators are working on a new project. Meanwhile I would look into the used market or the new Vesc Express logger. It seems to be a capable unit, but I also think that the software is not as finished as Metr.
I am using the 30A BMS, not 60A. I am not using my VESC through the BMS so discharge ratings don’t matter. Only the charge rating matters, and it is 20A for the 30A (discharge) model of LLT BMS.
You should not connect packs with different parallel cell counts in series. Unless the actual battery capacities are an exact match, you’ll end up discharging the lesser battery more, which may not trigger a low voltage cutoff early enough. This may cause the lesser battery to discharge too deeply, which damages the cells and makes charging dangerous as well.
Also, water-cooling for the VESC is probably not necessary. And it’s definitely not necessary for the battery. For me it’s enough to have the VESC in an aluminum box. It doesn’t even conduct the heat anywhere, but still stays cool enough.