There "were" some stainless steel 1 gallon tanks made that would take 3 or 4 8x10 SS film hangers, but the most common "tank" for developing moderate quantities of sheet film up to 8x10 is the 3.5 gallon "deep" tank. Kodak made several models, and Cesco had their Cesco-lite ones. These tanks have lids, and are designed to be kept full of chemicals. You would need 4 tanks...Developer, Stop, Fix, and Wash. These types of tanks can take up to about 12 film hangers at once, if you can handle that many at once in the dark. So you could develop up to 12 sheets of 8x10, or with double 5x7 hangers, you could do 24 sheets of 5x7, or with quadruple 4x5 hangers you could do 48 sheets of 4x5 in one processing run. You choose a developer that has a long "tank" life, and one that can be replenished after each use to extend the life. HC-110 is one such developer.
The wash tank does double-duty as a water pre-soak tank prior to the developer. After the film is in the fix for a minute or two, you turn on the lights, dump presoak water and rinse the wash tank out and start filling with wash water.