I know a couple who are travelling around the world on their Moto Guzzi at the moment.
They have rigged a canopy on their motorbike and cannot speak highly enough of it. They like it so much not because it keeps the rain off them but because it keeps the sun off them.
Kitchenman...I am sorry to say this but your flags leave a lot to be desired.
I used to have an ICE Trike and a Bacchetta Giro 26, both were very low to the floor and so I thought a flag was needed.
I conducted my own tests and the very first thing I found out was that the size of the flag matters. Too small and you do not see it and too big you get a lot of drag. There is quite a fine line. I am surprised you could move forward with 2 shopping bags, it is a bit like a drag racer throwing out his parachute.
Colour is very important. I found day glow orange was best during bright daylight but dayglo yellow was better on cloudy days and at dusk.
Material is crutial because as most of the bike flags you can buy disintegrate at an alarming speed. They fade almost as fast. I am have lots of orange and yellow day glow offcuts from sails. The material was designed for storm sails to be used in the Southern Ocean and so is the best material you can get for bike flags.
I am fortunate enough to have all the technical software to design flags and a sail cutting laser to cut the cloth etc, etc. I used to be asked for flags and now they are being ridden all over the world.
You would think something like a flag is simple but it can get quite complicated.
Day Glo orange and yellow vests are possibly the best material you can to make your flags with. Make them triangular, abput 50cm long and 15cm deep. I found that is the best size to make them fish tail.
You can also buy small circular kites on e bay that let the wind through are bright and move a lot. They are fun and good.
Steve