I spent four months on the road last summer and visited 35 RV parks. During our visits, we encountered one reversed polarity issue, two low voltage problems, one bad ground, and one dead line on a 50A supply. We were using a Progressive Industries EMS-PT50C electrical management system. Granted, there were no surges detected, but these other issues could have caused equipment damage or malfunctions, and I'd consider the bad ground a safety issue.
At the very least, I'd use a surge protector in areas where even a distant lightning strike could cause a sudden surge on the line. But an EMS may save you a lot of hard earned money if you have to start replacing air conditioners and other appliances.