I am in a similar boat, riding mtb and racing enduro in daylight hours on the weekend and trying to get a bit of zwift training happening at night after putting the kids to bed. I have just started the Crit Crusher plan which has a wide variety of stuff and appeared to be the best fit for Enduro as far as I could tell.
From what I can gather pedalling fast is good practice for going fast (and raising FTP) so I have also thrown in a few zwift races for good measure.
I have a race next weekend (middle of training block) and one a few weeks after the end with a planned taper built into the plan so I will be interested to compare my times against previous efforts on the same trails for both races.
I would be interested to hear what you do and how you go?