For me the bigger the front wing the smaller the tail. My smallest foil works best with a bigger tail. 375 or smaller with you foil, the longer the fuse, the smaller the tail you need. My biggest foil works best with a tiny tail. Don't be afraid to go smaller than you think possible.
I once lost my tail with the original 1150 and rode it thinking something wasn't right, wasn't till I got to the carpark did I realise the screws weren't done up probably, and it went for a solo swim. But it still rode but in super pitch sensitive mode. Wouldn't have been saying the same on a small foil.
Try the smallest you can demo with the 999 and spend 3 sessions before you decide if it works or not. But it will be faster.