You could choose the 25L cube... and brew to 21 or 22L. That'd be just enough head room in the cube to pitch and ferment. The square 25L jerry would allow you to squeeze much of the O2 from the container before sealing.
Plenty of people do it.
A while back there was stirrings about a Kegasaurus 20/30/50L polymer kegs with a commercial A-type valve.
https://www.beerandbrewer.com/oxebar-updates-one-way-keg-technology/
Are these still a going concern? Did the project ever get off the ground?
Are there any available for purchase?
Any...
I've used a 20L handy pail with 2 kettle elements for about 10 years. Works great for heating sparge water. You may need to run separate elements from different outlets to avoid tripping fuse box or use a 15/20amp outlet (air con, stove etc). Do a search for "bucket of death" on here... plenty...
Castors fit no problems. I just used a hacksaw. A little bit of effort, but not too bad. If I had to do any more I'd make up a jig to hold the legs in place while cutting. The rough end fits inside a sleeve under the bench, so my dodgy workmanship was concealed ;)
For my Braumeister 50L, I went with this square stainless work table and these castor wheels.
I cut the legs down to give a table height of about 640mm.
Up here in the tropics we’d use mauri 514 ale yeast. Perfect! Dry, neutral and temperature tolerant.
Anyone know of a Qld distributor? Postage from Sydney is $34 for 1 tin!!!!
The Nut Brown Ale was my go to years ago and a real crowd pleaser! For simplicity the kits could not be beat! I’d still be brewing them now if my LHBS still stocked them.
I occasionally think about wearing the postage costs and ordering a few for old times sake. IMHO they’re better than any...