IP67 is a pretty low standard, I think its essentially the product sitting in a bucket. It does not account for much spray.

I remember talking to Garmin once and their IP67 ratings do not cover spray. As a matter of fact, I was told my IP67 unit is not covered for direct rain which Garmin states can reach 60 mph. Garmin recommends the spray bag.

Im not too fimiliar with the IPX ratings, however Im not sure that a rating of "8" means you also get the protection of "1" through "7".

Use a spray bag.