Surface shield is just as good or better. You know your stuff, good for you! I do at least one application before winter, and on my car with a little rust I do once more in the late spring as well. The stuff doesn’t seem to harm rubber, so I go crazy and spray it all over with my little 5 gal air compressor and a woolwax gun. Beware, it makes future underside work much dirtier, but I much prefer that to battling rusty bolts.

Invest in some fluid film or other lanolin based undercoating, that way you can stop the road salt damage from getting any worse.