Well, Pigmeat, here is the logic. Do you want the freedom to switch between SSB or AM? Well, yes. That could mean a class AB/C switch or just a big heat sink to take the calories. Class E and D are indeed interesting to a newbie engineer type who wants to play on the bench. Yes, advances are HEAT less . The Baseband for any mode on shortwave unless we are talking a digital mode and if that be the case a BIG BAD linear amp will be needed.
If you are an equal lover of broadcast and engineering, after some thought and not wanting to REINVENT the wheel. I would choose a BIG BAD high gain FET (low drive) broadband amp. The exciter would be a DDS low power am or SSB exciter, 10 watts, or less with a pad to adjust drive.
BIG OLD BAD 100 volt or so DC powersupply. And you are set. There are predesigned FET amps with heat sinks in the KW range unfinished except for enclosure, harmonic filter and what ever else you want to throw inside the case.
An easy 250 watts HIgh FI am transmitter is born. Its NOT rocket science. Let the hard part be done by somebody else and not you because you will spend months just reinventing the donkey cart.