What do you find clunky about the mobile observatories?
As a deployable they’re easily deployed in response to a cloaky camper entering a system if you suspect the cloaky camper is not paying attention.
And as a deployable it’s easily killed by the cloaky players if they are paying attention, which makes nice stationary bait that you can use to catch them in action.
A single bomber can kill the mobile observatory in about 6 torpedo volleys, so if you put your bomber-catching cloaky ship right next to it you may get an easy kill if your suspected AFK cloaky target happens not to be AFK.
The mobile observatory makes interaction with AFK cloaky players possible and even encourages interaction with cloaky players that are paying attention (without forcing them), which makes this a great tool against AFK cloaky camping as it doesn’t interfere with regular non-AFK cloaky gameplay.
A structure would be a much bigger investment and would likely be active in a system 24/7 rather than ‘in response to a ship that may be AFK’, which would have the unwanted downside of interfering with regular non-AFK cloaky camping. And a few cloaky ships cannot take down your structure, so you lose the ability to bait them with this change.
An easily placed and removed deployable makes much more sense as a tool against AFK cloaky campers than a structure, if you ask me.