Yes, you can. However, keep in mind that if you do that in RSRDC, that you stand a good chance of ruining all of the good timings that lurker spent on the various groups that he put all that research in to. The Mission Editor has a very ~nasty~ habit of changing some settings on groups. Just be certain that you "cancel" out of any group you look at, and do NOT change anything. If you want to change something, look at it in the Mission Editor to find the grouping, then find it in a text editor, and edit it that way. You can Save changes made in the Mission Editor, but put the file saved into a mod folder, and then run WinMerge on it to see what the changes are that the Mission Editor makes. It will surprise you... but you can put those changes back with WinMerge, but be careful with the edits you want to keep...
P.S.: Some groups do go in/out the north entrance, some the east, and others still out the other south entrance. That's only two "layers" there, not seven of them... Most of the convoys and merchants in 1943 to use the west and south side though...