Welcome to the board!
I'm moving from my ST1100 to the CTX1300. I've been using a Garmin Nuvi 550, same waterproof and glove useability as the Zumo except no hard buttons and it cost a lot less than the Zumo and does everything I need, on the ST. I have a
Garmin branded cradle and RAM mount on the ST similar to this minus the handlebar clamp mount part. I used just a RAM ball alone on a bar across the top of my dash. You can see it installed in some of my photos in the photo gallery. I liked the Garmin cradle better than the RAM cradle for the same unit since the Garmin cradle seemed to lock the GPS in better. I plan to move the direct connect power cable, cradle and RAM arm that I have to the CTX and get a new
RAM ball handlebar mount like this to mount it. That will be clamped to the left side of the handlebar and set up so the Nuvi will sit low on the bar and in front of the left speaker (don't need to see it, only hear it). If you're coming from the ST1300 you probably have seen many options to install nav on that bike. I see this as the best set up for this bike since there isn't much ledge on top the dash to mount stuff. Exactly where you mount items like this is entirely a personal matter. Some will use a RAM ball on the reservoir cover or on the reservoir clamp bolts. Some will put one on the center of the triple tree. I had my GPS in the center like that on my GW and again on my B650 but decided that is too low for me. I want the GPS up into my line of sight more so as not to take my eyes off the road so much. I would think you could find a mount that will work as well for the Zumo. I'll try to remember to get some photos of it installed.