I have been into 4x5 for the past 30 years.
My basic aperture has been f:22 for all lenses at 4x5 inch, exept for the Imagon ofcourse.
What I have understood is that the increase of DOF is 1/3 towards you and 2/3 away from you.
With a TC you have tilt to increase the DOF.
Using tilt (frontstandard only) should be done in small steps of 1 degree at the time, esp outside.
It is so easy to set the tilt at 15 degrees at once and than increase and increase and to find out that 3 degrees was what you needed.
GAS: RB, Sinar P2 4x5 and 8x10 inch