Actually, I think the convoy raid missions would be more in line with the assassination/capture/kill cargo missions.
I am still trying to get the one I am working on to work and it is fairly simple, yet a PITA to get right. This is not as easy a project as just slapping some ships together in a point.
There's no conceivable difference between this and say a mission where you are going to shoot somebody and destroy - tractor cargo (like the escape pod). -just- have to change what reinforcement your victim has.
I support this idea of yours, but then you should also provide adequate missions for fighters/bombers as well as for caps, because it wouldn't be quite fair that caps have all the fun would it?