Well to stir the pot some... There were definately a lot of airfields used in WWII that were nothing more than fields of grass. I'm talking about unimproved. Take a look at a lot of the RAF forward response fields used during the BoB. Yes you can land an an "unimproved" Vehicle Hanger and get a sucessful land so why not anywhere on the actual airfield?
All the Best...
Jay
awDOC1:D