The latest "Farm Show" publication displayed a link to a small company selling vents for portable fuel cans. These appear to be the same type that were installed on cans back in the "good ol days", and almost as expensive as the whole can from back then, ($4/per IIRC). If I can find the rag, will post the link in case anyone is interested.
Probably illegal to retrofit a modern day can, but if you still have some of the older cans laying around, or like me, just disgusted with the now-a-day setup.......
By the way, Jill does appear to have a nice display of.....er......ahem.....cans!!!!?