I had the benefit of a corporate budget which may influence adopting my following advice. I did an internet search and established handling agents at all of the airports. I emailed them with requirements reagarding ETA / Fuel / Customs / Onward weather brief & Flt Plan requirements / transport to/from hotel etc etc That is the business that they are in and every stop went to perfection. Timing is of course flexible and the bookings for Paris had no cancellation fees. My timing brief was ATA +1 hour for transport to the hotel, to allow time to put the aeroplane to bed and that timing worked fine.
This is an interesting procedure which I know someone else employs apparently successfully. Like most GA pilots I have always tried to avoid handling agents and ended up having a lot of hassle as a result, and I suspect in many cases ended up paying mandatory handling anyway so I may as well have taken advantage of the service.
I suppose the downside is that one gets hit with a £100+ bill every place one lands.