If terrain is a problem, explore doing the "restricted L-O-S" option on a smaller space?
The advantage (space-wise) to this is that how far one can spot is severely restricted, so that both the Patrol Phase (iirc, the 'lock-down' range for this is modified to 6"?) and maneuver ability is preserved.
The disadvantage (game-wise) is that any combat is guaranteed to be 'up close and personal', though that is its own challenge not to be dismissed. Stalingrad, anyone?
Urban rubble is common to any theater, and can be indicated by the simplest stuff...scraps of cardboard torn up and put in a heap, a knocked out tank, a crashed aircraft, ...?
I realize it may not be the prettiest table, and as a 50+year model builder there's no one in front of me in the queue to bend down and exclaim "ooo!...take a look at this!", but I also know that the game (CoC) is so good that when things get going you could have blocks of wood on a piece of plywood and no one would notice.