Do an initial comparison of the stand to the ground… then…
Do it on the stand.
In other words, just like Gary, Tony and TJ say.
When you’re driving, the load on the front end of the kart, even with the wheels pointed straight ahead, is always changing… under acceleration, under braking, riding over bumps, etc. There is no such thing as a static load on the kart when you’re racing… so what does placing a static load on the kart, while on the ground really add to anything over putting a static load while on the stand?