I've been full timing for 12 years and only 3, maybe 4 times over those years, camping in over 100 campgrounds from Alaska to the Yucatan have I felt I needed one. Especially in Mexico. I will say that after my 2nd computer motherboard was killed by bad electric did I finally do the research and settle on a wired in EMS Progressive brand unit.
As it turned out, after a heavy rainstorm, the display unit went bad, but Progressive replaced it free. Only had to give them my CC # until the bad one was returned. Plus it's made in the US, AND it has an easily removed & replaced surge board so if lightening kills it, you only have to replace the board not the entire unit.
That Progressive is a 30 Amp, and now that I've moved to a 50 Amp RV, I am selling it on Craigs list. I think it's OK to put the link here because it's a public posting:
Surge Protector