Even with a legal MM card, you might run into issues at airport security or customs. It’s worth checking the rules for SXM because they might have specific regulations about bringing in marijuana, even in tincture form.
Instead, you might want to consider CBD products if they work for you. Some French-side pharmacies in SXM carry CBD items, but it can be hit or miss. Another option is to use something less noticeable, like vaporizers or edibles. You can find some good ones at https://www.smokeday.com/brands/focus-v.html/. This could make your travel easier and still give you the relief you need.