Jeff-Understand your frustrations and ideas as I went through many choices similar to yours not long ago.
I mostly shoot landscape when not shooting street.
During a 3 week trip a few months back with my new M 240, perhaps too many lenses were packed, but who cares with a backpack (and a wife). In addition, I wanted to be prepared for most situations. This trip consisted of mountain terrain a lot and desert some too. Valley shots worked well with the 28-90 and also shots for future stitching.
I decided to take the 28-90 R, 15/2.8 R, 21 SEM, APO50 M, APO135M, APO70-180 R plus a 2x R extender which I only used for about 10 minutes in 3 weeks. I was so taken with the 28-90 it was used about 75-80% of the time. Maybe it was a novelty for me, but I found in my situations it was a wonderful choice. I try not to crop at home, so using the 28-90 lens by cropping with the zoom, my images would not have to be cropped in PP, loosing some of pixels we pay so dearly for.
If you want some of the best glass made, get Leica. You have many choices from M to R lenses with the M 240. Using the EVF is THE way (actually the only way) to shot when using the 28-90. The red in focus area takes some getting used to, but after a while it just works and is intuitive for me now. Also I loved to see where more depth of field occurred when changing F stops in Live View as it helped when framing landscape shots where you have plenty of time to frame and decide on depth of focus options.
If you have eye sight problems count on using the EVF. I have a 5D3 for wildlife and action use and it is a dream for my needs in these situations. The 70-200 is fantastic even with the 1.4x extender.
I have only one eye working and find the Leica RF very nice especially with the new LED frame lines, but wider than 28 they will not help and you will need the EVF anyway. Keep in mind R lenses ONLY work with the EVF unless you are winging it or going so wide that DOF concerns are minimal like with the 15/2.8 R which is one of my favorites.
Sure, R lenses are bigger than M lenses. Just look at the lens mouth and that will become obvious. I find a combination of M and R lenses is a fantastic option for M camera users now and brings in a whole new spectrum of glass available for us now. The beauty is that if you want a small package use M lenses on the M and if that is not important for say landscape/tripod work then you can use all the R glass you can afford. Frankly, I like the tripod mounts built into the larger R glass.
Hope my experiences help. PM if you need more comments.