I was able to remove the maxtemp error from the main screen by changing all the temp_sensor lines to 0 in configuration.h. I don’t know what it would take to remove all references to temperature in the displays. I’m not sure I want to do that – I may at some point want to hang an extruder on this thing and print something big.
I would be interested in what you find out, though, Curt. This is probably a good place to start: http://www.marlinfirmware.org/index.php/Marlin_Configuration.