Interspecies hybrids between Maxima & Moschata

This is a curiosity question for Joseph Lofthouse, as well as anyone else that has experience breeding or perpetuating hybrids between these two species.  I'm aware of tetsukabuto squash, and recall reading in the past there have been other "scientifically" produced interspecific hybrids.  I thought I remember reading where Joseph Lofthouse has kept a hybrid population going, but I don't remember how it was done.  Do you alternate planting the hybrid seed amongst maxima one year, & moschata the next & so on to keep it straight?  Or do you just plant them amongst both every year & let the flowers & pollinators figure out which pollen will fertilize the fruit?  I'm just curious what multiple generations of this looks like, & wonder when/if it becomes stable enough to self-pollinate within its own population?  

The Tetsukabuto F1 plants don't have male flowers making them sterile.

I grew them in a big field with all other types of squash, and let the ecosystem figure out how to pollinate them.

In the next generation, some of the offspring regained male flowers, and I presume fertility.

Based on the shape of the leaves, and color of fruit, it seemed like pepo squash pollinated some of the plants, but those plants didn't produce viable seeds or offspring. Viable seeds might arise if I choose  different pepo pollen donors.

The offspring mostly looked like they got pollinated by maxima squash. I don't know if that's because that cross retains more viability, or because maxima grew closer.

In later generations, I grew the population in the middle of my squash field. I selected for thin vines and peduncles, to repel squash bugs. I selected for that wonderful maxima flavor.

Thank you Joseph for the clear answers to my questions.  I'm glad to hear about your progress in this project.  It would be nice to have a more SVB resistant vine with Maxima-like fruit, very cool!