Distributing run/power (marathon) + bike/power (4-6 hour races) training

Question on blending run/power (marathon) + bike/power (4-6 hour races) training:

Situation: I am simultaneously training for 3 subsequent(ish) races:
-March 6: Hilly gravel cycling race (Dirty South Roubaix, 62 miles, likely 4 hours)
-April 24: Nashville Rock’n’Roll Marathon (hilly AF)
-May 16: Mountain gravel cycling race (Belgian Waffle Ride, Asheville. Wafer, 77 miles. Likely 5.5-6 hours)
*Using Steve Palladino’s 6 flday marathon training plan + TrainerRoad’s cycling with power plans (emphasize sweetspot and interval over Z2)
**I’m a triathlete, usually training 8-10 hours/week. Bike FTP 302 (3.3 w/kg), rFTP 376 (4.2 w/kg).
***The above marathon was postponed twice last year, as a result I trained twice but never got to raise it. The benefit is a lot of quality marathon training that will serve as a base/foundation + I raised my rFTP significantly.

-Do better on the marathon than the gravel races, BUT maintain my bike FTP/fitness and not be mid-pack in the 2 gravel races

“How do I pack ENOUGH bike training in, without it taking TOO MUCH away from quality marathon training?”
*Can some bike training even benefit my running as is often the case in triathlon training? Or at least not subtract too significantly?
**Is it OK to sacrifice SOME run Z4/5/6 training to avoid burnout (since the bike training is mainly sweetspot (Z3/4) and a slightly longer Z2/3 ride per week?

Proposed solution:
-Marathon run training: 4 runs/week (1 long, 1 z3/4/5, 2 x ez runs)
-Bike: 2 x week (1 Z2/3 90-120m + 1 x sweet spot)