We had them fitted as an extra to our last M/H, and used them once in 3 years. It was particularly windy, and they seemed to make little or no difference. Current M/H came ready fitted with them, and we've never used them. I certainly wouldn't pay any extra in future to have them, and in fact may well take them off the current vehicle. I'm sure others will have similar views, just as I'm sure others will think the opposite!
Rick
Rick