Gas can (rotopax) venting

So I recently added a vent cap to my water rotopax so that I could run a spigot. I am planning on adding vent caps to my fuel rotopax as well. As we all know, gas cans need to be vented with elevation and temperature changes. Until somewhat recently (in California at least) gas cans had a little plastic snap-to-close vent cap that would pop open on its own if pressures became too great. You'd get some minimal gas splashing out that little hole. I found this to be convenient because the can pretty much vented itself. However, this is definitely not up to safety standards by any means, and for rotopax mounted on a rack, that gas could find its way to your paint. For a majority of my trips I'm climbing 6000-12000 feet in elevation and in the past my rotopax has let fuel past the gasket from pressure if I didn't catch it in time.

These are the vent caps I have currently

$14 Magicfour Fuel Gas Can Vent Caps, 6 Pack Fuel Gas Tank Vent Caps Gas Can Replacement Vent Plug Gas Jug Vent Caps for Gas Fuel Water Can Jug to Allow Faster Flowing

https://www.amazon.com/dp/B08747LWC4?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

My idea is to attach some sort of splash guard or additional vent that would only release vapors while driving to my destination. I would then immediately close those vents after arriving and before setting up a camp/campfire. I might use something like a pneumatic dampener such as this

$19 DOITOOL 3sets Compressed Pneumatic 1/4 Industrial Air Noise Dampening for Pneumatic Noise Reduction 8pcs*3

https://www.amazon.com/DOITOOL-Compressed-Pneumatic-Industrial-Dampening/dp/B0DRMP5TTB?th=1

or a breather valve such as this

$5 Yourkar 2 PCS Aluminum Gas Cap One-Way Breather Valve Fuel Tube, Fuel Tank Vent Pipe for ATV Off-Road Motorcycles, Motorcycle Accessories (Black, Transparent Hose)

https://www.amazon.com/Yourkar-Fuel...ocphy=9031172&hvtargid=pla-2281435176698&th=1

Can I get some thoughts, other things you've done? And no, I don't want to switch to Jerry cans, they also build pressure and nobody makes ones that are quality. Even the high-end ones like wavian the anti-rust coating is dodgy and you can scratch it off with your fingernail, no thanks.