I had personal effects in a sea container sent in from the States and went thru the same... again, WHO you deal with, and how firm you are... determines which part of what law will be applied to your case. As we all know, the SAME situation can yeld different results in France, not because the law is not clear, but because people are moody.
Proof of change of residence: I had to call the States and have a government agency state that, as a matter of fact, I had changed residence. The letter looked official and had a stamp. The statement of change was based on the fact that I had applied for a new passport and that on the new passport, there was a French address. I paid for a special courrier to go pick up the statement at the gov agency in the States and Fedex it to me pronto (I was threatened by the broker to have to pay for wharehousing because without proof, my container was sitting on the dock in Marseilles... and would start costing for each extra day after the initial few days that are free).
The custom broker I dealt with in NICE (office at airport) and who was taking care of the "dedouanement" in Marseilles of the sea container "tried" to scare me... with something like, "the customs have the right to open your container (sealed container) in Marseilles, and to inspect it... and to open ANY box they wish inside the container... and if they find something they think they should tax you on, they will." (I think these brokers have a load of tactics to scare people like us and this is their way of having fun for lack of better things to do).
But lucky me, a friend of mine USED to be in that very same business and told me that there was NO WAY the customs could open a container without me being present, because it would be too easy to "frame" me. So, what this meant was that the container was NOT going to be opened in Marseilles. What a relief. Like you seem to be, I am based over by the Antibes area and it would have been terrible to have the dedouanement done in Marseilles.
Anyway, feeling strong-ER with that information, I called the broker and replied, "No way, never heard of such a thing as dedouanement in another town than where the owner is and don't you dare tell me other wise..." then magically, the broker changed his song and said that "exceptionally" (don't you love it when the French do things that they normally should do but make sure to let you know is done "exceptionally" just for you) I was VERY LUCKY and that the dedouanement would be done in Nice (which BTW, I had paid at the other end, in the States, to be done in Nice).
However, he insisted (with his petty power) on telling me that even though my goods were personal effects, if they contained anything of value, such as furs, jewelry and what not, I could still have to pay tax on those items. I asked if this applied to things that were 20 years old, and he assured me that it did! I said that I had paid taxes on these things already at time of purchase, and he said that the French government didn't care! Some mumbo jumbo about the French system having the right to tax on a "Value" that the customs PERCEIVE the item to be and not the actual value of the item even if it is on a receipt (the reason being that the customs would have no proof as to whether the receipt was bonafide or not).
I insisted BACK that the customs SHOULD have better things to do than to bother a petty customer like me with only personal effects... and that I COUNTED on him (the broker) to protect my interests... (by that time, I had changed my know-it-all-tone to a poor-me-what-would-I-do-without-you-tone) as I had more family coming from the States, and even a large company owner who wanted to relocate his ENTIRE company to France before the year end... and that it was a good thing to know an efficient broker and to be able to trust him (my tone had again changed to something like you-know-what-kissing).
So, the container was delivered to me (in the States, I had paid for door-to-door service) still SEALED. The only time I spent was on the phone with the broker as related above, and when I went down to his office at the Nice airport, to pay for various taxes and fees. There also, it was a bit complicated, but it was a banking specificity that was solved in one day... and that was it.
The moral of the story is: stand firm, know your rights and... get someone who speaks FLUENT French because it seems the brokers allow themselves more moodiness with foreigners than with their own. Also, a French speaking person will know when to sound MAD and when to PLEAD... the usual combination for successful communication in France.