Thanks, I'm back from my trip, never got it to work in France. Well briefly it must have because I did get the disclaimer message.
The APN was correct (it auto populates). I had Enable LTE on (never seen LTE speeds while roaming internationally but kept it on because there seems to be some reporting on this thread that they've seen LTE speeds) and had roaming On as well (I turn off roaming when back in the US).
I'll try different combos of settings next time.
But I set it up this way and it worked in Amsterdam, Italy and briefly for a layover in MUC where it roamed on the German T-Mobile network. So I thought these settings would be universal.
I have a trip coming up next month in Vienna and Prague so will be interested to see if it works in those cities. Only spending a couple of days each so probably not worth spending $20-25 or more to get local SIMs there.
If that doesn't work, I may just stop paying for the month to month Simple Choice data-only plan, though it's cheap enough to be useful in the US.
I'm suppose to only get 1 GB but whenever I check my account, it shows zero data usage. ANyone else see that?