I checked on the iPhone 6 running iOS 2.14
The workaround works perfectly when autosuggest is enabled … when autosuggest disables we remain with a gap … but as you already stated the amount of users still stuck on iOS 12 is so low… Even much lower for users stuck on iOS 12 in combination with auto suggest disabled.
So you’re fix is the best I can imagine. Thx for sharing ! 
