I've got a Raymarine Dragonfly on mine, with just the silicone jacket on it - 2 summers with it and no problems so far.
It's mounted angled so it's partially protected behind the front seat, away from the worst of the splashes but still gets wet.
I remove from the boat & rinse briefly under the tap & dry after each sail.
The advantage of the hand-helds is the in-built battery, saving you from having to mount the battery in the hull which is a bit of a faff, but there are plenty of guides online such as this one
https://www.kayakfishing.blog/blog/installing-a-raymarine-dragonfly-5-pro-to-a-hobie-outbackI did something very similar with a clippy food box, but using Ctek connectors so I could plug the charger straight in.