This might ease your pain a bit.
I just finished editing a new terrain and placing 26 fields w/o any problems. The method I used was to turn on autosave in both terrain edit mode and object mode set to 1 minute.
After every field was placed before I switched back to terrain mode I clicked autosave again.
The work around for the field 1 crash is easy to get past, lay down 2 fields then use the field number switch mode to swap them, then delete field 2.
