All fair comments, but I'm talking about some kind of a specific dispensation or reassessment of limitations to allow something like an increase to, say, 635 kg (extra half hour flying time) with the restriction that you are operating to and from ground effect (eg departing an airfield or similar), possibly airspeed restrictions until you're under 622 kg, and whatever else was deemed necessary.
If you hover taxi over a flat surface for a short period, do an airfield departure, then use restricted power / speed until a bit of extra weight burns off and go on your merry way, then it doesn't seem unreasonable to me that that would be as kind or kinder to the aircraft than lots of things that get done to them in the course of normal training.
16 litres extra fuel would put the C of G further back for that initial stage, which would be a good thing, and without knowing where the actual limitation lies it's hard to say what would or wouldn't be possible as far as extending the envelope a la the Bell situation.