Yes, interesting, and one of those things we need to get clarified, probably!
It has been done (marcus (the other REALLY crazy one) did a DIY of well over 2000km.
I think he had to set it up as an "ordinary" Permanent, rather than a DIY. (See 2011 Results for Marcus Y.)
If he'd entered it as a DIY "1000", the longest option available on the online entry form, he could have ridden his whole entered 3400 km (shortest), but would have had to average 13.33km/hour for the counting distance, and would have scored a mere 10 points.
On the paper entry form though, you can presumably enter for any multiple of 100km, including 700 and 2000, etc.:
http://www.aukweb.net/users/common_files/Handbook/entry-form.pdfOn the website, at
http://www.aukweb.net/diy/traditional/it says
"We validate rides at 50km, 100km, 150km, 200km, then at 100km intervals up to 1000km."
Elsewhere no limit is mentioned:
Handbook:
9.6.1
Distances are registered and validated in increments of 100 km from 200km upwards.
9.6.2
The
standard distances are 200, 300, 400, 600 and 1,000 km.
On speeds:
9.7.1
The minimum speeds are:
for events registered as 200 to 600 km – set by the organiser within the range 14.3 to 15 kph;
for events registered as 700 to 1200 km - 13⅓kph;
for events registered as 1300 to 1800 km - 12 kph;
for events registered as 1900 to 2400 km - 10 kph; and
for events registered as 2500 km and over - 8⅓kph.