For your mash out use a custom mash step which is set as follows.
"Auto Calc."
"Infusion"
"Step"
Water to add: Calc (greyed)
Water temp: 212F
Target Mash Temp: 170F
Step Time: 5
The "Water Temp" should be set at the temp you will heat your mash out water to. It needs to be pretty hot or the calculator will one up with a huge volume to add.
The above settings will compute the volume of water at 212F needed to raise your mash to 170F.
I don't use the above settings. I always use free form and just add 8 quarts at 212F. 8 quarts is much easier to measure and gets the job done.
For batch sparge I have a 3rd step: sparge. The volume required for that step auto calculates based in prebiotic volume and the mash in and mash out volumes.
This is basically what I ended up doing. Thanks for the help.