Many thanks Genghis!
I'll probably wait until the summer heat has passed, in the interest of engine cooling, but I will try to follow your guidance. I will need to fit a rudimentary OAT probe to find density altitude, and would probably start climb tests with a high airspeed and decrease in 5 kt increments. I don't have a CHT gauge, and don't want to climb more than I need to at very low airspeed.
The flight manual gives an ASI position error correction to give Equivalent Airspeed, which I assume is the same as CAS?
As for the calculus, if I had been told as a child that it had a practical application to flying, I might have paid more attention in class! I'll tackle that one when I get to it.
Adrian.