I commute on my trike about 355 days a year (all days except when snow is plowed onto the shoulder of the road), and I need to pick up mail, and have sufficient storage to carry my cold weather gear home, on days when I don’t wear it on the ride home. I had a rack, and panniers, and they worked fine, but I wanted something lighter and that didn’t make the Speed look like a utility truck. I got the $14 Nashbars triangular frame bags at Bruce’s suggestion, and they are great for summer commuting. I still needed a little more storage for winter use.
I saw all the room under the seat and thought I could use a PVC pipe to use that space. But I found a Pickett blueprint carrier which is very light, and with its screw top lid is totally waterproof.
It can carry my rain pants (in stuff sack), my rain coat, gloves, and head covering. They also have extension sections, so I can add another section for longer loads. it would also be perfect for carring lunch, as long as its a round lunch, like bagels, hot dogs, donuts, etc. This tube setup seems light and aerodynamic, and is working well.