There's a handy chart here:
http://www.rvupgradestore.com/Articles.asp?ID=279that lists and shows a comparison of the features of the various SurgeGuard and Progressive surge protection devices.
There are 8 30amp models listed. 5 are portable and 3 are hardwired. The chart helps you sort through the features and the cost of the devices and would be good to narrow down your search. You might want a device that offers Ground Fault Shutdown for example. Then visit the manufacturer websites to confirm the info. The chart shows that the SurgeGuard 44740 for example doesn't have Surge Protection but that is not accurate.
The Progressive EMS-HW30C seems to have the most YES answers in the chart for the 30 amp models but it is not a portable unit.