okay, so here's a modified proposal:
in order to keep it as simple as possible while optionally expanding it, I would like to propose the following changes, to be introduced in this order of priority:
1) loot from mission sites is not teleported to the base, but
divided into two stacks: all weapons, ammo, items, live aliens and stuff that soldiers carry or that is on the floor of the transport craft when the battlescape ends are put onto the xcom transport craft (and unloaded to the base once the transport craft arrives back home). the rest (alien alloys, elerium, UFO components, Alien bodies) is added to the transport queue, arrival time is calculated by distance as if it was transported from another base.
1a) loot in the hands of a soldier or on board the transport craft (i.e. dropped inside) arrives at the base with the transport craft (skyranger etc.)2) after a mission is completed, the mission site changes into a "clean-up site" (marked by a different color) for x hours before the "transport" starts. (x=? fixed value by mission site type? depending on amount of loot? IDK.
for game purposes, the site is basically an "xcom base" that the aliens immediately know of - so it can be attacked by a standard retaliation mission (*) )
3) a mechanic is introduced that saves the "state" of mission sites (terrain setup, damage to terrain etc.) after the battlescape ends.
3a) "clean-up sites" can be attacked by UFOs, adding a new mission type: "clean-up team rescue". the mission site is the same as before: it retains all damage from the original fight, loot is partially piled up, storage crates are standing around, (armed?) civilians are present (the clean-up team), UFOs/alien bases are partially dismantled (parts are missing, like nav consoles, power sources, some walls etc. - it should be possible to randomly delete objects, right?), and fresh aliens are roaming the site.
4) a mechanic is introduced that shows transports for
transfers on the geoscape. (adding the transports for
stuff you buy would create too much trouble, I guess - where is the stuff coming from, anyway?)
4a) these transports can be attacked, too.
for mechanics purposes, if the transport happens to cross the path of a UFO within the UFO detection radius (or passes an alien base within the detection radius), a new UFO will be spawned at a randomly chosen heading and distance from the transport. this UFO immediately travels towards the transport at top speed. as soon as the UFO catches up with the transport, the transport will immediately crash. the UFO will "land" on top of the crash site immediately - that is, both the transport and the UFO will disappear to be replace with a new mission site: "transport crash site". the mission site (for battlescape purposes) is a landed UFO site with a (yet to be created) crashed human cargo plane. a few (armed?) civilians (the flight crew) are present, otherwise the mission plays as normal. if successful, loot previously on the transport craft has to be recovered by means of a "clean-up site" again...
I think 1)
needs to be introduced. all others would be really really nice, but 1) is a must.
(*): about retaliation missions: are they spawned randomly, or do they happen only at the end of the month? because these missions should happen more often, of course