So it seems, after more research, that if you want a stable platform with a display usable on a sunny day without shade or hood you have to go with one of the CrystalSky displays.
That is correct. My iPad 9.7 works great, love the big, clear screen etc. downside is it's hard to see bright sun, but I don't think any device is much better in that respect other than CrystalSky screens.