It's do-able. If I were the roofer putting in those skylights, I'd want
them as close to the top as possible, to minimize the amount of water
they see. The pop-top skylights are great, and seal well when closed.
Get quality curb-mounted types, and you'll be happier down the road.
They all have their thermal problems (condensation, fogging, etc.), but
a good double-glazed model will minimize that. Got no idea what you'll
be charged for installation, but get a guarantee in writing against
leakage from the installer. Tom