Hey Don,
I took my own advice and looked up some T/O figures in the POH of a '77 150M for you. It says to add 15% for dry grass runways.This is figured at 1600,max gross.
At 30c/86f on dry grass you need 989 feet (860+15% for grass) and should clear 50 feet by 1744feet from a pressure alt of 500agl. I extrapolated between S/L and 1000 feet from the numbers it lists for for 30c to figure 500 feet.
At 104f/40c I figure you'll need 1064 (925 plus 15%for grass) and will clear 50 feet at 1872feet.
BUT; at 95f/35c I figure you need 1027 to roll(893+15%for grass) and will clear 50feet by 1808.
So I'd say you can fly from 1200 feet if you are careful and there are no obstructions.
My figures may not be perfect. I did figure this in a hurry, but made three examples. I'd welcome criticism. The lack of obstructions make a big difference, I was thinking about how those trees look.HA HA.
The landing figures are no problem at 52kts/ 40 flaps.
