Where in the country are you ? If I'm passing during January, I can drop one of my spares off f.o.c. (fibreglass rod, with Hi-Vis orange flag on top) I put a bid on
Ebay a few years ago for a bulk quantity - ended up with 25 for £3. Surprisingly, I've not needed them all).
You could use the standard fixing supplied or use 2 x rubber-lined "P" clips (
https://www.ebay.co.uk/bhp/rubber-lined-p-clips) to fix them in a suitable place on your trike. One size for the flagpole (6mm diameter), one size for the tubing on the trike, but join them together with one bolt. When I had my Performer, I used a 7mm internal diameter aluminium tube - with a bolt in the base to stop the flag pole from slipping through - to allow me to remove the flag when putting the trike back in the garage.
Merry Christmas
