A 7 wide inline will do a little better due to the lower cg in side winds, but It's still the same size sail for equal length trailers.
Having tugged about every kind of trailer around the country in about every possible condition (except windy enough to blow me off the road, thankfully), I don't think there's an appreciable enough difference in deck over vs inline trailers to matter when it comes to towing in bad weather.
I would get whichever suits your needs or wants better.
Looking for a new(er) trailer, stepping up to a 4 place from a deck/2place combo, I was open to inlines as well as deckovers depending what was the best deal. Found a deckover Charmac and couldn't be happier. Having the width to park 2 sleds side by side regardless of how pudgy they were, ability to shuffle them and get up to 6 machines in a 4 place, and just the additional covered space inside the trailer for whatever means it's needed is preferable to me.
If I was a high miler with the trailer, using it thousands of miles every year consistently, the 1' narrower trailer may be of some advantage, but being used as a primary sled garage for 350+ days a year makes it way better to have a wider trailer.