Inserting filament material change  

Inserting filament material change

Hello all.  I have seen several topics about color changes, which seem simple, just click the (+) on the preview, but I am trying to switch materials from PETG to TPU to create a stamp.  Currently the print is oriented with the PETG handle on the bed, with the TPU at the highest point.  From what I have found out it sounds like I need to add custom gcode at the material shift, an M603 first to unload the PETG, an M109 to get the extruder up to temp for TPU.  and an M600. to load the TPU and purge the nozzle. I am unsure if all this is needed, Just the M603 and M109, or if an M104 would be better/worse.  This is my first time looking into the gcode itself.  Everything I have had to do thus far has been able to be set up using the slicer settings.  

I'm also concerned about the MK4 and its ability to detect filament types.  Will this be an issue when the TPU is loaded and get an incorrect filament type error? 

Model picture and sizing:

Size: 15 mm x25 mm x32 mm

PETG 0-29.8 mm

TPU 30 mm-32 mm

Thanks in advance!

--Mike