Having done Uberman in the past, I'd like to recommend a few tweaks and general advice.

1) Consider swapping from 20 minute naps to 24 minute naps. The optimal is 24 minutes asleep with 1-2 minutes to fall asleep. I can't seem to find the original article by NASA atm, but here's an article referencing NASA's original study on optimal naps.

2) Devise a program to get from part 7 to part 10 instead of "try to space out longer". I did a standard uberman schedule and going even 20 minutes past my appointed nap time would immediately put me into sleep deprivation which risked oversleeping an alarm. I'm not sure how you plan to soft adjust to longer spaces between naps, but just winging it while sleep deprived seems like a recipe for danger.

3) Stock up on food. Expect to eat 50% more.

4) Make a list of things to do while sleep deprived at 4am for the adjustment period. I thought I was going to learn a new language with Rosetta Stone; I ended up reading fanfiction and watching through TV series. I simply didn't have the mental juice to do anything until after I'd adjusted.

5) Set up a sleep cycle calendar so you'll know what you're going to do every wedge, and what you're doing every day. It's very easy to lose track of days on a polyphasic schedule.

6) Buy a sleep mask. It's so much easier to sleep during the day with one.