In the 71-80 bracket AV a good win is around 140k XP.
Every enemy tower you destroy is 14k
Every own tower that stands is 14k
The same counts for graveyards, I think
Maybe mines too
Killing the boss is 18k
It can be a viable way to level or something to do while waiting for groups (like I do).
The one trouble I have experienced is that there is no 80 or close-to-80 to tank the boss which then results in a loss.