The sortie rate and tempo of ops from the carriers can be monitored from a civilian air traffic control and shore based maritime shipping radar, a few of which must be collocated with Houthi headquarter staff. Obviously they won’t be able to monitor everything but with the assistance of skilled advisors, the internet, some crypto, mapping software, etc they could probably put together a fairly decent, real time positioning of ships and aircraft. If they got a drone into the glide path of the Hornet tankers landing to refuel it could be dicey*. But that’s asking a lot from a semi trained, non professional militia. Other non state actors could do it, certainly they have tried…
At night, in a congested airspace, with many distractions sent up to occupy systems and attentions, “wear down the guard” so to speak.