I’ve used a single drum Thumler Tumber Model A-R1, rated for three pounds (of rocks) for several years. If I remember correctly, the Model A-R1 motor is the same as the one used on the dual drum A-R2 machine. I’ve easily cleaned over 20K pieces of brass with nary a problem.
My capacity may be a little less than what you need. My standard mix is roughly a pound of brass, a pound of stainless pins, enough water to cover the brass 1/4" to 1/2", a small amount of Great Value dish soap and 3 to 4 pinches of Lemishine. Seal and tumble for one hour for simple cleaning or 1-1/2 to 2 hours for super clean and shine. Some of my standard barrel loads: 150 pieces 9mm, 100 pieces 40S&W, 80 pieces .45ACP.
Because I’m dealing with a small capacity, I can easily use the kitchen or bathroom sink to rinse and separate the brass and pins. When I first started using the stainless pins, I picked up a couple of nested colander/bowl combinations from Wally World for around $1 or $2 each(?). Instead of holes, the colander has slots which are perfect for allowing the pins to drop through into the bottom bowl. Takes about 3 minutes to rinse and separate. (Just make sure you clean out the kitchen sink before washing dishes!)
A lack of planning on your part does not necessarily constitute an emergency on my part.