first your level looks really nice

yes, it is right trace_booster isnt good for your level,, but it work also with mdl, not only with wmb blocks
in the second picture: i see,the mountains, that really dont look so nice, write:
d3d_fogcolor1.red=80;
d3d_fogcolor2.green=100;
d3d_fogcolor1.blue=150;

just try my small script, perhaps it helps.