Just to circle back on the question; I ended up buying a Surface Go 2 with a keyboard/cover & an arc mouse (that folds flat.) Computer, keyboard & power supply total slightly under 2 pounds. It's 9 5/8" x 7" so small enough to fit snuggly in my Ortlieb handlebar bag. I a believer in the idea I shouldn't haul more crap than I need to (which is a corollary to the "try not to make myself slower than I already am.")
I ran into a cul de sac with my ipad mini. Couldnt get it to work. Might have been the keyboard version I got but I suspect it's a fundamental issue with what IOS is designed for.
I saw the bit about changing apps. I've no doubt there are more, better, faster apps out there than rwgps. Unfortunately, because the clubs, groups, rides, etc that I do all use rwgps, rwgps is my church. For better or worse.
We'll see if I actually opt to haul it with me. My next couple trips are fairly short and are in areas I have some familiarity. Emergency rerouting less likely. Regardless, I really like the petit size of the Surface Go, that it's a legit computer, light weight. Honestly, I think I could survive on this thing day to day. I'm mostly a mac nerd but frankly, I've been in technology for 30 years so there's not much romance left in any of this computer stuff. Yet, I'm pleased . . .
appreciate everyone's help and great thinking here! If you find a Surface Go laying by the side of the rode while you're out on a ride, you can assume the love affair ended and I decided I hated the thing so much I refused to wait for a garbage can to get rid of it!
John