Hello Tom
Welcome to FADU - I hope you find us friendly and helpful.
Reading your opening post you are finding 5x7 film development in a tray real a pain.
Someone has just brought out a new commercial slosher tray for sheet film - see here -
http://www.film-and-darkroom-user.or...ad.php?t=12928
They are caller slosher trays as after loading the film in them - developer is sloshed about (ie the tray is rocked from side to side and front to back to make the developer spread reasonably evenly across the film)
Alternative DIY solutions are discussed on the FADU forum - just put "slosher" in to the forum search function.
Martin