I have my remote switch mounted between the left grip and clutch perch. If that's where your comp. release is, try moving either one on the inside of the clutch perch. Some riders skip the remote switch when space is limited.
My alarm is zip-tied to the wire bundle behind the headlight. The only advise I can offer is to get some practice programing it and study the manual. It has a lot of functions to memorize that can help if you know how to pull them up.
I've got a smoker so the decomp. lever is not there, but had a DR so I know waht you mean. Have you considered moving it to the opposite side of the clutch lever? It may look odd, but not having to use it often, out of the way for the remote buttons.
My horn is zip-tied to the rear face of the Al dashboard, on one of those cable tie pads you can get @ electronics shop - they come with two hoops for the plastic tie to slide thru, & use 3M double-backed tape to attach to any flat surface. Hasn't come off for all my riding & washings.
You're gonna like the P3 (not that the others are bad); the horn feature allows me to concentrate on riding until it toots, then simpy adjust speed accordingly to bring the Diff. time as close to -30- as I can for the upcoming possible check, & usually roll in remarkably close to 30-sec.