I do this trip every year in a helicopter. You may have more range than I have.
My stop off (re-fuel) points are LFOH (Le Havre), LFQG (Nevers) and then LFML (Marseille). No ground handling agents required anywhere at these airports. LFOH fuel accepts the UV Air card but the others I have to pay by Visa.
Landing fees are about 15 euros at LFOH, 5 euros at LFQG and about 20 euros per day for parking at Marseille.
For parking at Marseille, just call General Aviation +33 4 42 14 25 00 to organise parking. There is a small terminal there and they are very helpful.
I did get ramp checked by the Police last time I flew in there (a couple of months ago) so have all the paperwork with you (CofR, CofA, licence, medical, etc). Very nice blokes though.
Enjoy.