PeterP makes a lot sense here. Prone has as much to do with SUP as it does with short boarding. Why not make it part of a short board teams event? [}:)]

As far as the Wildcards in the SUP divisions go, the Surfing Australia argument runs along the lines that they receive funding from the Australian Government and they are expected to post results in the form of gold medals.
In their opinion, sending Jamie Mitchell and Justin Holland instead of the second ranked performers at nationals provides a better chance of securing gold medals. It is of course debatable whether the likes of Beau O'Brian or Jackson Close could win gold anyway, they probably could. Nonetheless, Surfing Australia is backing in the guys they've chosen to get the job done.
If there's a precedent here, then I guess it is that you have to ensure you are the best performer overall at nationals, not the second best, in order to get to Peru.