Make all Federal Prison's self-sufficient.
There is no reason why Federal prison's cannot be revenue neutral. They have plenty of labor that can be used to generate "revenue" from within the walls of each prision. Revenue can be from the sale of goods or services (such as assembling products for a private company, for a fee), or it can be in the form of cost savings by having them perform federal services remotely instead of hiring a government employee to do them. Put them on stationary bicycles and have them generate electricity for the facility. Have them grow food on leased farms instead of buying food for the cafeteria. Have them do data entry for government agencies.
Federal prisoners should be doing something other than working out and learning how to be better criminals.