I would just get the tall 1/4 barrel kegs from Stout Tanks and go on without using glass. They hold 7.75 gallons, so you can ferment up to about 7.25 gallons (with care).
I'm working on a fitting that will allow you to ferment and then transfer to serving keg with a CO2 push. It will also have a thermowell that you can send a sensor down to get a reading from the center of the fermenting beer. I've been using a version of this setup for about a year (or more) now, with great results. If you want to go cheap you can use either an orange carboy cap, or a large universal bung with airlock. I like the CO2 push to extract the finished beer since it means zero lifting of the fermenting keg. So, you can ferment wherever you want/need and then transfer to serving keg. Once the keg is empty, then clean it (far lighter to do that).
Hopping Tango Brewery
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