The base can choose in this position whether he feels more comfortable sitting or kneeling. Kneeling, he can use the power from the thighs for a possibly necessary high relieving, but at the expense of stability.
The hands of the base are about shoulder width, as otherwise inwards turned hands of the flyer is the result.
The stability is ensured by the alignment of the line of power in the direction of the center of gravity of the flyer.
This is not a position for beginners, as they often tend to balance by using a hollow cross!
In fact, the base may only balance with arms and hip. The balance area is always within the range of the thigh -> no hollow cross!
No long arm:
In principle, in this position, the balance on the long arm is possible. Since the back of the base is very inflexible, he comes very quickly into the hollow cross.
My suggestion is to train these tricks exclusively lying or standing! The risk of injury is not worth it to me personally … your ISG will thank you!