Hi Jack
Doesn't seem that long ago you were on....time goes by quick....
I operate on 40M using a Class E TX / PWM combination....
Has never failed but its low power compared to you guys in the States...
This is a photo during assembly....

Hope the photo comes out showing everything....
I tried to digitally drive but gave up......so I sinewave drive with my only SSB rig Icom IC-735....
Requires appox 12 Watts of power .... and the output is around 110Watts.....
The efficiency is just OK at around 80-85% no more though.....doesn't matter running 100-120Watts really......
The output cores do get hot too after a while....will build another TX maybe in 12 months time as this is OK at the moment...
For your Class D TX I would Sinewave drive first as its easy to do and been all untuned you should not have too many problems....
The Low Pass Filter would have to be different from what you use on 160 / 80M...maybe JAY might give you details if you send him an email.....
Think have answered most of your questions...
Wayne