Yet another basin on stud wall question

I need to hang a 600mm wide, 35kg floating vanity and basin on a stud wall.

Wall is built using 3x2. Stud wall is im front a brick wall, built to allow hidden services and niches, so there's space to add larger studs / build a frame to support the sink.

How would you suggest is best to construct a frame, and, what size stud and fixings?

4x3 frame and coach bolts? If so, what size bolts?

Amazing mockup of existing studs, proposed frame and fixing points.

Not to scale.

Need to take the weight of an adult sitting on it..



Thanks for the advice

 

can we get a sketch of the adult sitting on it?

 

I'll do tbe sketch if someone confirms my plan will work, or, suggests a better one

Careful what you wish for, it might be me, not the wife, posing....