Best way to move to France as a freelancer?

I hope someone here can help. I have what I think is a unique situation and can't seem to find the right information to make my move to France... the right way. Here are the facts...
I want to move to France and stay indefinitely (perhaps to obtain citizenship if all goes well).
I am American.
I am self-employed. I am a freelancer and have my own company.
I work only for American companies and will continue to do that for the foreseeable future.
I have enough money to demonstrate that I could support myself for a year without working.

I contacted the French Consulate with this information, inquiring about a long-term stay visa and they told me to just write a letter that says I will not work in France while I am there... but I will, just not for a French company.
I want to be sure that I report things correctly because I don't want to run into further problems when I request residency and potentially citizenship.
Does anyone here have advice for me, please? My next step is to contact an immigration attorney, but only if necessary.
Thank you.