Just for the record, a video showing the "clearway" off the end of 27 at BRS (aircraft lining up for TO from 09). Which is, by the definition, effectively "infinite" since the ground falls away for a mile or more.
https://youtu.be/ZoQQ9AoKhwk?t=4m38s
OTOH, while there is no actual rule about where rotation should occur on the hard surface, relative to runway remaining, nightime centerline lights give a rather strong hint. They turn solid red with 1000 ft/300m remaining.
To me, that says "you really don't want to still have all your gear on the ground entering this area."
If your little green calculator still has you slower than Vr passing 300m remaining, IMHO, you were just a bit too "cute" in your programming assumptions.
OTOOH, I'm sure that the calculated V1 in the takeoff shown originally was adequate for ASDA. But suppose there was a loud "bang" right at Vr in that situation? Startle-factor, reaction time - would that have delayed their "just in time" rotation long enough to put them into the grass and approach lights?