Darn, now I need to research what a ’beer kit’ is

Some random thoughts from a 05 r1200rt owner. Could be off the mark, and it won’t matter probably in addressing your question though I have felt it was not until the r1250 opposed twin came out that bmw had an engine that felt like my old 05 does (too me that is a good thing the 1250 shift cam (if I said that right) came out.
So far as jumping horses goes…why did you get rid of the GS since you already have a GA? Was the RT meant to scratch and itch that neither of those bikes attended to? If so is the RT doing that and if so to what degree? The RT is Sublime in the way it’s able to deliver power, rain protection all in a quasi light weight package for a sport touring/touring motorcycle.
TFT screen…lord does any bike maker do it right yet? Maybe Harley or that Yamaha big v-twin air cooled touring bike…I cannot say. I do know what bmw came up with is not perfect nor great per say. No apple car play or android auto. It is what it is, just like I am guessing having to drill down into menus for heated grips and seat setting…maybe either/both could be added as a short cut to one/two of those buttons on the left side fairing (thought I had read).
R18…hum. For me it is a question of $ and am now retired with less of it lol. It is a looker for certain, but honestly other then ‘no one/few have one’ what itch is it meant to scratch (if uncertain refer to 2nd paragraph about

and determine that).
R18 details…I don’t own so could be WAY wrong. Big jugs/1800cc yes cool, space for feet below and above (they now have a fix for that) maybe not so cool. On subject of ‘cool’ will the bike overheat if stuck in traffic and it is 95 degrees out (I cannot say…some post yes, many have posted no issue).
Length and weight…your a fair sized guy so figure R18 weight is not an issue. If it is not then maybe the R18B or R18TC (both more weight).
Else be way cool and do a R18C. Realize the base R18/R18C have only 3.5” rear suspension travel (maybe sort of like a hd softail). Btw a youtube review comparing that harley and R18C was a tie

Though the C model comes with smaller front tire (better over bumps but maybe not as direct steering feel vs base R18).
R18B/TC will provide a happier rear end feeling (meaning your ass) over had bumps due to 4.7” suspension.
I feel the R18 is a heavy weight and not user friendly at low speed turns nor take off from a dead start (well less so). I would get all options if doing a R18/R18C…heated grips, cruise, headlight that turns into curves, the larger bmw seat (not base stock seat). R18B/TC comes with those goodies plus option for adaptive cruise control (if you do R18B/TC get it as I have read it works good…just not at detecting a motorcycle per say beside you or coming up from behind (if I recall).
Happy riding for only 100/150 miles then stopping…good the R18/R18C is for you if you like the basic look else R18B/TC If you want a larger tank. Want a color that stands out…get that multi-color option 719 and be unique..until you see another bmw with that color lol.
You may already know all these stuff so apology for the long message. Likewise owners of the R18 models can guide you from ‘butt on seat’ prepsectivec. I have only done a few test rides.
Does not sound the $ is an issue for you though for 2021 and 2022 models you get $2/$3k discounts plus thinking .09% rate.
I would love, maybe, that white RT color, well maybe it is an option 719 white (guessing/hoping a white Pearl color color of some sort).
Last, understand your needs/wants AND what they are truly if you are thinking of trading for a R18 having just gotten the RT. We all want the pretty girl (R18 any trim) but in life it is the woman that makes our life complete that will make us happier.
Depending on where you live that RT (aka cooler climate/mountains, great riding roads) is indeed an OUTSTANDING motorcycle and I would not dismiss it out of hand if owned for only a short while. I would guess you might not ever say the RT weighs too much, does not have enough power, don’t like the power band, don’t like the wind protection, storage space. Yes TFT is not great but one could live with it or add a Garmin gps to the handle bars.
p.s. Understand the R18 has a ‘happy’ rpm band range. I would not call it a ‘short shifter bike (aka honda nc700x) though the 18 is happier (aka smooth as glass) if keep in that band. No worries if running the engine above say 4,700rpm mind you, it is just the big jugs will start to dance weather you want them to or not

Last, if getting black R18/R18C make sure you get the white pen strip…she an’t a true old school bmw unless it has that on it.
Ride safe