Agree, getting up fast is key, even small chop or breaking rough small waves, are a lot easier to handle when standing up (not foiling) than when on your knees.
I have found, that even an okay volume board, if too short, is horrible in rough conditions.
Length helps a lot - in particular if the wind is on the low side - which it WILL be now and then.
I got myself a tad longer board, a bit less volume so thinner and superlight also - works so much better in these conditions (for me)
Anyways - getting up fast is what its all about, but if too low wind, you HAVE to ride a bit on your knee(s) sometimes - but try to avoid it.
Peter