agree with MikeC above. I did exactly the mod you mention. I put my zumo 665 and a V1 on the bike. I used the PDM60, and it has been 100% trouble free x 3+ years. The Eastern Beaver unit is good, used it on my 2004 and 2009 roadsters. There's also the hexcan unit.
I have accessory lighting (motolights), the zumo, the V1, a gerbing's thermostat for my heated liner, and a USB port wired to the PDM60, all steup to stay on for different customized delays. It just works
My advice is don't go looking for the gps plug, just put on a fuse/breaker block. There are people who'll swear by that, the white gps plug, approach, and it may work fine for them. I thought the delay terrible, just long enough to make it a hassle at a gas stop for your garmin. IOW you have to watch it to switch to battery power...and I always missed it, so the garmin would shut down and I'd have to go through the stupid reboot sequence of the garmin and BT connections with phone and Sena. With the PDM60 I can set the delayed off to up to 7 minutes, long enough to refuel without losing power.
BTW when you do this you will NOT have functionality of the wonderwheel at all.
I do not use my V1 on the bike anymore as I just don't speed like I used to, so why have the clutter---obviously ymmv as well as your speedo.
The next question you'll ask is what wire to use for the trigger wire for switched power. I use the taillight, and have the pdm60 mounted under the rear seat---had to move stuff to make room; others mount elsewhere.
Good luck