While all this is highly interesting, remember that the A300 and A310 are both well out of production, so if either of those were chosen, they'd have to be well-used second-hand ones - and both designs date from the '70s.
But there seems to be nothing available "off the shelf" for the duties you're talking about, and any conversions are going to take many a moon to go through all the to-ing and fro-ing that seems to be "re-equipment procedure".
Gloomy picture, innit ?
