USB ports have a parasitic drain. Id run that through a relay for switched power.
Voltages sound ok? What battery are you using?
Key access etc with the HDB setup is problematic. I sent a bunch of parts (triples, key barrel, speedo) to HDB for development but haven't heard anything back. Seems at a minimum it can be easiest to cut the edges off the key to allow it to fit easier. I tried a couple of options, none of which were ideal, including mounting the key barrel off the HDB top clamp. It's a big barrel!