Nomad, can't see any logic in flying at any speed other than Vx for obstacle clearance, especially if that speed is less than Vx.
TOSS is normally set as 1.2 Vs in the takeoff config. Bear in mind Vs changes with weight, so short of having a card with varying speeds for weights on it (assuming your a/c has a wide enought range of weight to worry about it), why not refer to the POH?