i've said it before, i'll say it again. pyrex carboys are the ticket. anywhere from 9L up to 36L. made of borosilicate. heavy wallled. fit a #12 stopper in the spout. have a beer making supply place drill a hole 24mm wide (the 24 in 24/40). then you can place a claissen in the stopper and affix all sorts of goodies like overhead stirring, addition funnels, and condensers. if you find one that is aspirated, voila! 20L sep funnel.
performics of admirable size are simple... use standard glassware for the distillation. multi-kilo size MeAm reactions, same as above. fair sized Al/Hg Amalgams with foil and MeNO2 if you're still into that.
two ways i can think of to heat them, should you need it. get a large institution size pot that will fit the carboy and fill it with hot water of the desired temperature. alternatively, get a heating tape. like a heating mantle, but in a flexable, sometimes rubber coated, long ribbon. wrap it around the carboy as many times as possible, then connect to your mantle controller.
these ARE NOT, repeat, ARE NOT beer and wine making carboys. same idea, different material.