My FH levels folder takes less than 2GB and it only has the maps which are specified as required for running FHSW. Those are the maps from FH 0.7 and Fan Mappack 6. Since your folder is larger, you must have other custom FH maps there, which are not required for FHSW. You probably should delete or move these maps because some such maps are known to cause FHSW to crash on some maps. I've explained this before:
I think some of you may have some custom maps for FH (such as from PFC mappacks or Fan Mappacks other than FH Fan Mappack 6) which are known to cause crashes, specifically on maps such as Remagen and Midway-1942 and maybe others. We haven't determined exactly which maps cause the crashes, but what fixes the problem is removing all map files from Battlefield 1942\Mods\FH\Archives\bf1942\levels that aren't from FH 0.7 or Fan Mappack 6. Usually, if you order the files by date modified you'll see that the FH 0.7 map files are dated 2005, Fan Mappack 6 map files are dated May 2006 and all map files dated after 2006 are probably custom maps which you can remove. If you are not sure, or the "date modified" is not right, you can remove the whole folder and reinstall just FH 0.7 and Fan Mappack 6. If you want to still be able to play those other FH maps too, have a copy of the entire Battlefield 1942 directory with all the custom FH maps in, and start FH from there.