You do know that you can buy rapid fixer in 1-liter bottles don't you? Tetenal used to sell even smaller sizes. I would think you would have to process very rarely to have a 1-liter bottle of rapid fix go bad on the shelf. It so, you could always split it into two 500ml bottles. The full one will keep for two years easily, then you'd have six months to use up the other 500ml.
Working solutions will last six months in full, tightly-sealed bottles as well.
If you really want to use the pre-packaged Kodak fixer, do do clearing tests and keep track of the proper fixing time, which will vary between 5 and 10 minutes depending on the state of exhaustion in the fixer.
Note also that many believe that conventional sodium-thiosulfate-based fixers are inadequate for T-Max and Delta films due to the higher amount of silver iodide in these films.
Personally, I'd be more comfortable using conventional fixer for prints than modern films just for this reason.
FWIW, I use rapid fixers one-session for film. I usually have enough film to develop (or I wait till I do) that I can mix 500ml of working solution, process all my film and toss the fixer into the silver-recovery jug at the end of the session. The practice of mixing a liter or two of working solution and then putting a roll or two through it now and then over the course of weeks (or months) is just begging for problems, with conventional fixers as well as rapid.
Best,
Doremus