Hey Damo,
Hope I'm not too late replying. I'm down from Hervey Bay for this weekend also at Rainbow. This arvo (Sun), your best bet would be a downwinder from Rainbow to Inskip before you reach the bar. SW'lies are due today and then turn SSE this arvo. You can kite the inside of inskip on a SW, S or SE but you would want decent wind as the tidal flow can really move in there. We will likely head to DI when the tide drops and may do a downwinder back along the coast into Rainbow. DI won't work in these conditions, you need some northerly. If you do decide to kite at Inskip, head right out until you see the 4wd only sign, there is a path heading left which brings you to a decent spot. There will be little beach there at high though. You can walk a hundred metres to where the tree line ends and the beach opens up to the actual point where the barge lands, don't get caught out from the point though or you may end up on Fraser, at least the barge back over is free!
Steve.