My favourite seems te be 35min, although I tend to use them as cheats, during weekdays I tipically get 4h of sleep wake up to drive my girl to night shift and after arriving home and time being 4:30 am I can't fall asleep right away, so I use a calming music for 45min folowing your 35min binaurals. Seems to work. I used your 90min sleep cycle but the result was not as good. Either is not optimal though. Any advice?
Sounds like your sleep schedule should be conflicting pretty hard with your circadian rhythm! If you aren't able to do anything about the schedule, you'll need to start getting crafty with the use of bright lights and red goggles to simulate the sun rising and falling when you want it to.
Dejan Kocon