Interesting discussion here, I've asked my current LAME also and he seconded the tank sealant idea, in his experience that has worked best in the past. Again a messy job, but apparently worthwhile.
Connaught, the plan had been all along not to take the windows out, I didn't want to make the job that big if it wasn't totally necessary.
I'm in two minds at the moment, I'm leaning towards the 'neutral cure not so messy sealant' option in conjunction with a cover, with the cover of course having additional benefits protecting the interior from fading and the avionics from heating up too much on a hot QLD day..