NP Brendan,
I wonder if a thin client setup may work? Again, I know nothing about all of this or whether it's possible or not. We have thin clients set up at work (which aren't actually thin cause they're full desktops), but it's a bit different cause each computer is actually fully functional with grunty hardware inside, but all of the programs are run off the server (graphics run locally I think). There are some very small thin clients available i.e.
here and
here
I realise that you'd still need to run things from a computer, but for the backyard astronomer, that's easy enough and you'd just have to run the ethernet cable into the house). If you're talking about portable setups, then back to square one!