Hi Paul,
That seems an awful faff to have to fit an extra tank. I have a D34 so not aware of this issue with the 36 (so will get back in my box). I get a bit twitchy when we get the tank to 50% and carry 2 20 litre cans to top up if needed. Please excuse my simplistic view, but I can see an advantage in making the primary filter accessible.
Best regards
Angus
The membership association for owners of Dufour Yachts