I suppose if you really wanted to you could grab the amounts available at every point on the price ladder (from the API or the graph display), and those bet at SP (without limits and at every price point a limit bet has been placed) and run them through the SP algo as documented at:
Or you could set your market view to show both "Near" and "Far" SP projections and see if the actual BSP is close to the "Near" projection?
Neither method would take account of "take SP if unmatched" bets, unfortunately, which can skew things if significantly large.
I suppose if you really wanted to you could grab the amounts available at every point on the price ladder (from the API or the graph display), and those bet at SP (without limits and at every price point a limit bet has been placed) and run them thro