It seems French DGAC is creative sometimes :
They now have a new hotel/restaurant which seems very nice .
Interesting! It was such a shame they had customs / immigration removed. Could a French speaker call the number and ask how it works ? Is it possiable to fly from the U.K. again?
Just called this phone number. It’s the mobile of the airport manager. He told me they can ask the Prefet for customs to show up for special events. The are special requests and they are agreed in most cases. But they won’t come for a single airplane.
The more aircraft involved, the best chance to get it.
So a EuroGA fly-in should be OK :)
He confirmed 100LL and UL 91 are available with cash or standard credit card.
It is really interesting that an airport in France offers this “special service”.
A few years ago I was at Biggin Hill EGKB and some bizjets were departing for Toussus, Paris. I commented to a colleague (one of the pilots) and he said “client is happy to pay… everything is possible”. So evidently a deal was done with French police to allow this, in return for some payment. But this was never in the AIP. Knowing a bit about how the bizjet scene works, it could have been €500 and the client would have thought nothing of it, because the flight Biggin-Toussus in say a CJ3 would have been billed at a few k anyway.
Obviously €500 would be ridiculous for our GA but something like €100 would get business because it will save an intermediate landing, the fee, the extra fuel burn, and is much safer. Two intermediate landings actually, in most cases. Last time I did an intermediate landing in France was 2014 and I am not the only one.
Historically, French police virtually never turned up anyway, so everyone was a winner 
The Service de l’information aéronautique is now compelled by law to issue an official list of French border crossing point. (At last!)
https://www.sia.aviation-civile.gouv.fr/pub/media/store/documents/file/l/f/lf_circ_2017_a_031_en.pdf
The VAC (dated 2015) has not been kept up to date, and I’m afraid that it won’t be possible, at any price, to obtain a special service at Abbeville, as it’s not in the list.
The airport manager didn’t mention any cost at all for the exceptionnal customs check. I am sure there isn’t one.
It is a service meant to allow groups of GA/UL pilots to enter Schengen/EU in a cheap and easy way (non TXP..).
In France, every law has an exception 
Arranging a special border entry point can certainly be arranged in France. And not just for the deep-pocketed clients of bizjet operations. It’s arranged every year at St Omer LFQN for a type fly in (Jodels from memory). The aeroclub organise it and the cost to participants is zero.
I remember it was tried by people from here for the fly-in to Melun. No success. I guess it depends on how good the organizer’s relations with the public French GA organizations such as the FFA are.
Quick update :
I went there with friends (4 POB in a 172) last saturday for dinner at the airport restaurant.
Still Air-to-Air radio. A helpful guy is present until SS or 9pm (whichever sooner) to take the fee (9,60€ for a 172) and sell fuel. 100LL and UL91 available with CCs.
Good food at the restaurant. It is also a hotel (so you are good if your aircraft decides to break down there ).
I departed after SS, activated my FPL with Lille FIS/APP (open H24), and aimed for LFPT among the Paris lights (and several fireworks around).
Just an amazing view and experience !
My passengers were most impressed by the ease and beauty of GA that night !!!
Lesson learned : enjoy the privileges you worked so hard to get !
