I have some 26 x 32 conferencing grid paper (stuff for stand up easels) that I made my maps on, using other 8x11 paper tossed on to simulate the fog of war. Mostly, each of the level maps can be split into a North and South section. I draw each starting at the north and south and work my way to the middle. The middle section then duplicates on each map giving me encounter space I can play in until I need to switch from north to south section. This way my double map is never all on the table, just the large half section the party is in.
If you count things out, 32x26 x2 with middles overlapping works for s decent number of levels. Once things got to big I then taped 2 sheets together to make 40x32 x2 maps with duplicated middles. This even helped me increase the space of the map dimensions to account for the 7 person party I'm running.
Needless, I now have a large roll of maps.
Hunting grounds is next, and I will probably just make that into sections, use some generic maps, theatre of the mind and what ever else to get through that huge level