There is the old method of you carry a powder horn. Pour from the powder horn into a measure. Pour from the measure into the muzzle of the rifle. Even the simple pistol horns can be used in that case. Fill the metal pistol horn and dump right into the measure.
http://www.cva.com/products/access_load.htm so you need a powder horn, powder measure, and a #11 capper is handy as well to carry and cap your rifle.
Another method is pour pre measured charges in to speed loaders. Carry as many speed loads as you think you might need.
http://www.cva.com/products/access_hunt.htm
I like the pre measured speed loaders because I carry five of them and a loaded rifle for the day. That means I have six shots to work with. I have never needed the full six. Then carry some projectiles in an altoids can. Line the altoids candy tin with cotton patches. You can use them for swabbing the barrel in an emergency. Also the patches will keep the projectiles quiet and protected. Some patches on top of the projectiles as well helps.
The St. Louis Hawkins is a nice little rifle. My friend's son has one. He shoots 70 grains of Goex 3f and a patched roundball. So far for whitetail it is all he has needed. Welcome to the sport and the forum.