From: The Great White North!
There was some discussion on this a while back: http://www.matrixgames.com/forums/tm.asp?m=4518454
There are three methods or transport:
Cargo: as you're discovering has great granularity but some tricky bits and doesn't do everything
Lua: An advanced teleport which some really good options
Teleport: The old standby but has the main disadvantage that the unit has to be on the map somewhere. I often put them on an non-aligned side, at a polar opposite to the player, they switch sides when they teleport.
All three are useful, all three have their place and all three have disadvantages. The designer just needs to balance it out and decide. You can and I believe should mix and match as required.
As serjames indicates: IOF#4 Gate of tears has a bunch of cargo stuff. I cannot recall if teleport is used but the cargo module and Lua are certainly used. Another one is 'Jar Heads on Ice' and a few of the lead up to the Iceland Amphib scenarios. Another is coming out shortly once I get my act together.
I think that 30 min is a good time estimate - perhaps a bit slow, but certainly workable - if its going to unload in 15 seconds, it won't take long to load. Considering that the cargo plane will have to conduct its standard preparation, normally 2-4 hours, which I think is good as well. People are easy, and everything else is either on pallets or wheels.
There are some bona-fide jumpers on the Forum - Airborne Rifles and Ultra-Dave for certain, who can verify that, but loading a Hurc is quick, getting off is quicker.