[Zeke]

While I think placing concrete inside is a great improvement, I don't think closing in the space up in the rafters is. I like the charm of open upper space.

For any practicality of a workshop and office in your climate, the main structure will be all but impossible to heat and cool. I'd build separate areas within the main building for these purposes while trying to highlight the overall feeling of the tobacco barn.

There are not enough pics here to go from, but what would a 2 story structure at one end look like? Maybe with an exposed staircase and balcony entrance to the upper facility.

Actually, the shorter building looks longer by proportion and might be the better candidate for something built at one end. At least you'd get a single story out of that.

Think also of cutting dormers into the roof.

Again, w/o pics, I can't see the possibilities. Could one be connecting the 2 buildings with new construction geared for the living portion be an option?