FWIW -- similar to what
@darrell (post #19) did -- I've been adding direct-to-battery Powerlet outlets to assorted bikes -- CANbus and otherwise -- for 15 years or so. This includes work on my new C 400 GT a few months ago:
This scoot was ordered through Max's (Troy, NY, location) and, without even my asking, as part of their prep work they installed an SAE pigtail. This is tucked underneath the bodywork somewhere, and I assume this was directly connected to the battery; they showed me where, when I took delivery, but I promptly forgot the location, as I don't like messing with SAE connectors).
The advantages of a Powerlet/DIN/BMW/Hella connector is that it's trivial, quicker, and easier, to connect than, say, an SAE connector.
The advantages of that location -- and I've been using this under-the-left-thigh location on all those bikes -- is that it's fine for connecting a smart charger or an air pump, but it's ideal (IMO) for connecting heated gear: power for heated vests and liners invariably comes out of them on the lower left, and your added connecting cord, in my suggested location, doesn't interfere with steering, doesn't get mushed against bodywork, is easy to connect or disconnect when seated on the bike, and won't be forgotten to be unplugged as you dismount.
I have a coiled cord (recall old phone cords, if you're old enough) with a male Powerlet on one end and a coax plug on the other end, for heated gear.
For smart chargers, I have a cord with a male Powerlet one end and an SAE connector on the other. I made that myself years ago, but you can buy these at Amazon, if you like: just search, for example,
powerlet to sae adapter there.
The on-bike socket I've been adding to bikes -- typically with 14-gauge wire and a 15-amp hot-side fuse -- is this one:
Individual Powerlet sockets for custom installations.
www.powerlet.com
So, I offer this type of setup as just another choice, and if anyone's interested I have a bunch of pics of my C 400 GT work for this mod in my gallery for that scoot starting with this image/caption:
I have a sub-gallery of doing this work on my former Victory bagger here (and this is the only bike farkle I've undertaken that involved the use of mayonnaise):
I'm not very familiar with the RT variants (I did own an R 850 R for three years, and now the C 400 GT, in terms of Beemers), but I'm guessing that there is a similar area in the bodywork that is suitable for this type of mod.