I recently sold my 20-bore flintlock fowling piece, but I can tell you what I did. Shot rode in a snake, Irish head. 2f powder in a horn, for both main and priming when hunting. I used 4f in a tiny horn for range priming. I only carried "overshot" (thin) cards and put 2 over the powder and 1 over the shot. The cards went in my waistcoat pocket.
I made a canvas double bag (a la T. C. Albert) and carried basic tools like turnscrew, knapping hammer, ball pulling accessories... You know the drill. Also had a ball bag that dispensed .600 RB, and patch material cut at the muzzle with a straight razor patch knife. Spit lube at the range, mink oil prelubed and precut afield.
I hated keeping track of all those cards and cushions that rose out of shotshell thinking, and enjoyed the freedom and simplicity of V. M. Starr's loading advice. Oh--horn, snake, and bag each had their own strap, bag and horn to the right, shot snake left.
Must have left something out........