With a grouser at top dead center on the rear sprocket you lay a straight egde across to the front of the track. my book calls for 2 inches of sag. It says tigher on dry conditions and maybe slightly looser in mud. I find mine runs best a bit tighter. I keep mine to 1-1 1/2 inches. Seems to work well for my conditions.

Sounds like you are giving it a good workout. Hoping to get to some woods road work myself shortly if the weather holds. 18 degrees here this morning, but calling for high 50's to low 60's by Monday.