This is certainly going to take a few days to get used to - but the idea seems quite reasonable.
After a somewhat abbreviated nap yesterday I went to bed at about the usual time (02:00) and set an alarm for 05:30 - allowing 30 minutes to fall alseep. In the end it took more than that (I kept glancing at the clock to check, which probably wasn't that wise); but probably no more than 45 minutes.
Getting up at 05:30 was more of a shock than having less than three hours' sleep, but I'm sure I'll quickly get used to it. Changing timezones in a short time (moving from Glasgow back to Sydney) didn't seem too bad.
The only thing that worried me this morning was that I had started yawning by 08:00. To tweak things slightly (and hopefully counteract the tiredness) I'll push today's scheduled deadlift session slightly later, and move the 90-minute nap to shortly after it (probably starting around 18:00 or so). Increasing the separation of the nap and main sleep period should help.
Update (following nap) :
Unlike yesterday, I had no trouble falling asleep when it came to the nap. No doubt this is a combination of today's rack pulls and the fact that I've been fairly tired all day. It'll take a while to get used to this.
That said, after a 90 minute nap I'm feeling pretty good - certainly ready to stay awake for several more hours. As planned, I had today's nap a little earlier (18:00 - 19:30), which bumps up the separation with the main sleep period. The way I feel right now, that seems like a very good move.