Posted for Jim Sower <canarder@starband.net>:
<... I am willing to predict that on a hot day he will be limited to 50-60% power
for any sustained period ...>
Don't bet the farm.
I'm no expert at all, but you've done your calculations using a lot of variables
that I've never seen measured accurately.  Perhaps you have.  47 deg difference
between input and output to engine/radiator is waaaaay higher than I have heard,
but I haven't heard everything.
Think I'll wait for someone to actually fly it in an airplane ... Jim S.