With an M < 5, I'm personally open shoving 88 from any position.
In 3rd position with 88 and 7 still to act there's a 17.6% chance someone still to act has an overpair. I calculated using this
preflop overpair equation I came up with previously.
So with an M of 4 and an 82% chance I have the best hand at this moment I think preflop shove is the best play here.