Trinovid,
The CAA produces guidelines that (generally) must be adopted in the OM as part of the AOC approval process. The OM then becomes the defining document.
So you need to get an alleviation from the CAA, which then has to be incorporated and approved in the OM.
To do this, you will have to show that "positioning by air" has no impact at all on max FDP, and your rationale will be that positioning by air is not tiring (or is just as tiring as normal home life). You will be met with some considerable resistance to this idea - mostly from pilots. If you believe that going to an airport, checking in and travelling as a pax for a 2 hour sector should not count in the slightest as FDP, then you also believe that I can be called in by my company, shoved in the back (as a regular pax) for a sector, and then have my FDP start down route.
You can't ignore a rule/principle just because it suits you on one day, and then reverse it because it doesn't suit you on another.
As a pilot group we have fought long and hard to prevent positioning sectors from being discounted from FDP calculations. If you want to be able to position on the day to suit your living arrangements, then you are asking the rest of the world to be positioned by the company on a duty day and have all the FDP calculations to be started after that positioning.