Tim, the Sporthill pants are truly amazing for windblocking. Mine have been used so much for fall, winter and spring riding that there are now wear spots the shape of my seat on the bum area.
They are a bit heavyish, well, compared to fleece only or tights, so I have never actually taken them on a bike trip, as it would have been overkill.
My tights are sort of medium thickness, with a bit of fuzzness that make them cozy, and I wear them even up to the mid teens celcius, as my leg muscles really prefer being warmer than colder.
There are so many diff tights though, its areally hard to properly describe one pair compared to another.

and again, I have friends who have no qualms with bare legs and cold, where I would be sufffffffering big time.

from what you describe, it sounds like some sort of tights will work, and you can put them on under long pants if you have them, or just the tights and shorts as you say, and bring out the quilt if need be if sitting outside.
Certainly will work better with something compact for your baggage space you have.