Ultralights:
"gusty winds = no flap, calm = full flap"
What sort of aircraft do you fly for heavens sake? A flapless landing on most swept wing airliners will mean an increase in landing distance required of around 100%.
For example, for a no flap/no slat landing on a DC-10 a 12,000 ft runway would be good.
That cuts the choice of airfields available down just a little!