FS9 Scenery map

I know one can use LWMview to find LWM files bur where would one look to find highway and streams. The reason I am asking is while I am making scenery I want to be able to disable default scenery. Take the North East for example what area is coverd per BGL? What file removed Roads what file removes streams, and so on. I hope someone has been searching this area and has an easy answer. I want to remove the area around West Virginia and want to know how far in each direction I must go.I guess it is not possable to for example to edit each LWM and VTP ASM file to tell FS to disable area in each file.Any help here?Richard