Not sure if possible, with the information available from Antonov,

But a take-off and landing performance calculator relative to the runway in use and meteorological conditions would be great!

-225 doesn’t derate thrust for take-off so it would be a simple can/can’t take-off within margins type deal.

Allows simmers to ‘realistically’ use the -225 at more airfields and nearer its envelope limit. 

Heya!

As a general rule of thumb, you'll need 3500m to take off when fully loaded. VR will always be the blue marker on your speed gauge, that one moves according to your weight 🙂

Understood,

However an actual performance calculator would be more useful in enabling a wider variety of runways across all weight regimes

It unfortunately is rather hard as the data is not readily available as you already guessed 😕 

Shame 😕