How easily can you measure 30m during competition?
The idea would be to restrict your throwing options similar to pure stand and deliver but with more flexibility where you can stand and deliver or have a one step follow thru if that's more comfortable as long as your step thru lands on the 30x30 mark. If you do this then you don't need any putting circle and the complaints about pure stand and deliver causing knee injuries is mitigated. In addition, players could stretch out to the side farther where they release to the side on the left foot and bring their right foot down on the mark after release.
In terms of timing, maybe you require maintaining balance behind your mark for the hypothetical 2-count where the group can see that you hit the mark properly.
Rater of the tossed arc.