https://cat2.dynserv.org/cat2/programs.html#Q3MAP2
I've edited the compiler so as to remove those restrictions ^^.
Motified Q3map2 Quake 3 Map Compiler: The (gpl'd) Quake 3 map compiler (q3map2) failed to compile my map "castlebunker" after it got to a certain point in hugeness. It failed because it kept erroring out due to hardlimits programmed into the code of q3map2. The errors were: MAX_EDGE_LINES and MAX_VISIBILITY_EXCEEDED. This edit raises the MAX_EDGE_LINES and MAX_ORIGINAL_EDGES to 16 times what they normally(65,535) are to 1,048,560. It also removes the size limit on visibility data (MAX_VISIBILITY_EXCEEDED).
Enjoy and tell me how you like.