Reverse Polarity Protection relay calculation
In a word, no.

You say your load requires 30 A, but your relay is only rated for 5 A. Relays are resilient and can handle a bit of pulsed overcurrent, but you're trying to use this relay for six times what it's rated for--it won't survive.

There are better reverse-polarity circuits out there, by the way. Relays are expensive, but a MOSFET is much less so.