Well, on my server, there are none of these "basecamping" rules, as we mainly play 16 player maps with 54 players in game. Its hectic. But, there is no way to not have infantry somewhere in bases that need taking out.
Let's take "Strike At Karkand" for example. The 16 player version of the map has 1 allied base, the 2 forward spawns, and 3 cappable flags all in a line (basically). If the allies take the first two, its taken down to only the back flag, which the allies need to take. So this would not be an uncappable and thusly would always be allowed to fire Artillery upon.
Likewise, if the axis keep the allies at bay, and the axis is shooting Artillery into the main allied uncappable spawn, where the equipment is. This should also be allowed as an APC could camp easily there, or they could just be holding all of the equipment from the game. The equipment spawns quickly enough after it dies, less than the artillery reload time, so it will always be possible for the allies to get it out of there.
Note: In the above, Allies is the USMC and Axis is the MEC/China. I've just played too much 1942.
