It sounds like you're starting a small business, in which case, you will quickly outgrow 5 gallon batch sizes as you begin distribution.
Depending on your needs, I would suggest purchasing industrial beer brewing equipment, such as conical fermenters and brite tanks.
Use of Conical Fermenter
The conical fermenter would allow you to long brew a batch, bubble nitrogen or CO2 up from the bottom for agitation (increasing extraction and preventing oxidation), and will let the grinds settle into the bottom shoulder of the tank when the brewing process is complete.
Use of Brite Tanks
Brite tanks come in a range of sizes from ~1 gallon up to tens of thousands of gallons. They are primarily used as a glycol jacketed pressure rated storage vessel for keeping beer (and similar beverages) in optimial conditions before storage. They may also be used as part of the forced carbonation of the liquid in the tank. A brite tank will be useful for your cold brew business as you scale up because it will give you an intermediary vessel to blend out and store batches before packaging.
Scaling up your production
Depending on your business plans and packaging / distribution ability,
you will probably want to start with a slightly larger setup that gives you 1) room to grow and 2) the ability to expand without changing process or systems. Beer equiptment is well suited to meet these goals.
Quality, consistency, and some notes on process:
The majority of consumers demand a consistent product with an interesting flavor-profile that they can enjoy every time they purchase your product. Flavor-profile deviations will cause you to loose consumers to a more consistent product in the long run. The following points will help ensure a more consistent product:
- blend out batches of cold brew from the fermenters into a single brite tank
- use CO2 or nitrogen to prevent oxidation
- manual agitation is inconsistent - use a bubbler with CO2 or nitrogrn instead. This will also help with goal 2.
- Packaging lines make a huge difference. Invest for growth in a rotary topper, not a 4 or 6 head.
- Don't attempt to use the same blend of beans for cold brew, draft cold brew, and nitro.