OK, I think it's gotten to a point where I can release it for limited public testing.
https://generalstaff.org/maps/spmbt-map-tool_V3.html
Search bar, lets you type in a name like Gettysburg and go there.
Lat/long are obvious.
N = make the map zone point NORTH again.
ROT slider, rotate the map zone around.
M/LEVEL adjusts the scaling per level of height.
CTR = Recenters the map zone. You will have to move the map or zoom in and out to see the new zone area if you hit this button. Current known bug.
GRID = toggles the hex grid on and off
NOTES drop down, lets you delete notes, etc.
SAT - Toggles satellite map.
90M Copernicius / 90M SRTM = switch between sources = 90M SRTM is what Venhola used. I got it set up for my website to use php to cache Copernicus maps on my own server; so the more people use it, the more stuff is cached and the faster it will be.
90M SRTM is slower to download, but you can run it without webhosting as a fallback; but it doesn't cover extreme north latitudes.
D/L ELEV downloads the height
You can then adjust the M/LEVEL scaling, add hex note points by right clicking on areas and ADD NOTE.
Then D/L MAP and it'll be downloaded to your download directory.
It was designed to work on a 1920x1080 monitor; so may not work well on smaller screens.