Corner fogging and air bubbles on BW 4x5

[Jim Jones]

I always presoak film in water with a bit of photo-flo before developing either on spiral reels or in trays. It was absolutely necessary when solarizing Tech Pan in Solarol developer.

[Randy]

...so how does one agitate a Yankee tank enough without the developer spilling out?

I don't think you can - and I don't see how one could possibly obtain uniform agitation in one (I have tried).
There are other tanks that are supposedly water-tight.
There are dip-n-dunk tanks using film hangers.
Or, as I have been doing for many years, just lay out 4-5X7 trays in the bathtub (if you can make your restroom light-tight) and process away.