Thank you all, your answers are very helpful.
Is it possible that the fact that many linear sets have two wound strings has more to do with balance in sound and feel (similar gauges instead of increasingly fatter strings), rather than with string tension and such?
I like the Southcoast sets a lot, but for several well-founded reasons, they don't offer a Baritone set with an unwound 3rd (or even 4th) string, which is something I'd prefer for my specific Baritone.
So I just replaced the wound 3rd string from the D'Addario Titanium Baritone set (.030W) with the unwound 3rd (0.041) from their Tenor set. Sure, it's fatter than the wound string. But since the 2nd string is identical (.033) and the 1st is very close (.028 in the Baritone set and .029 in the Tenor set), I figured that the 3rd would be interchangeable as well.
Actually, D'Addario is using those very same strings for some of their Guitar sets, so they will be tuned the same as on the Baritone but at a higher tension due to the larger scale. I guess what that means is that the same strings can actually be used for some quite different purposes... of course, this might not produce the best result to everybody.
My question, therefore, would expand further to how to use Guitar sets on your Ukelele? Many here, for instance, like Savarez Alliance 520/540 strings on their Tenors. Can they be used on a Baritone as well? What are the factors that one has to consider when using Guitar strings on a Uke?