Actually, I'm just using the main oscillator as the carrier so carrier parameters won't need any more room. Also, triangle as the modulator and carrier sounds great, it's even more plasticy than normal sinewave FM.
But indeed, more generators are needed for the wavetable to create all OPL-1-2-3 waveforms. It would be nice to have something like a stack of operations you do for a wavetable item and then save those in the song. So in the song you would just have data like:
1. generate sine
2. silence the last half of the wavetable
3. reduce to 1024 samples
or
1. generate sine
2. apply 5th harmonic
3. apply octave harmonic
4. drop lots of bits
And then when the song is loaded it would generate the wavetable items according to that and there would be no need to save the same waveform data over and over for each song. Though it's not like the waveform is gigabytes worth of data...