somehow the maps need to be designed in such a way that opposing forces can only reach areas where "hotspots" are suppose to be. OpFor shouldnt be able to get into the spawn area at any case. ofcourse this problem only exists with BC and CTF and therefore these gametypes should have their own maps designed to prevent spawncampers.
i had this idea in my mind too, and i think is a good idea,
a map thats specially designed for a particular game-mode,
maybe its not efficient to build a special map for each game-mode,
but there is an efficient way to do this,
for example, dem_snow should look simulair for obj or bc,
but... the bc version should have a bit more erea/rooms and stuff,
so the demsnow bc version should have locations/ereas opened that are normally closed by walls, if it was the obj version