Sounds long to me, even for someone who isn't hobbling round.
I always log my orienteering straight-line kms as miles.
Doesn't work in urbans really, but once you count in the warm up, jog back to the car etc,. its better than straight-line distance, and I can't be arsed measuring actual distance.
So, you're right but don't panic, I know 3 miles would definitely be too far for the sprint. And do come - can't remember if you used the Deanburn bit of the old map for training - its a great area .
We did and it was. Unlikely to make Sprint Scotland though, sadly.