Well, you'd still get the planet vision with ferang's suggestion, Orodum. It just wouldn't be indefinite. And, that's all you have to sacrifice to be able to get rid of allies' structures when you take over a planet they lost on their own. If you just wait, their structures will just go poof. Minus the idea of "surrogate parenting" anyway. I'd say the only way the "surrogacy" trait should apply is when the structures are also taken over by your forces. So, not only would you need a parent asset in the grav well, but you'd have to claim the remaining ships and structures also...otherwise they continue to degrade. If you got no economic benefit for maintaining these items, that would simply be parasitism.
In which case, Orodum, if you were simply aquired the structures and ships, would you really spend resources to replace things you got for free?
I think that'd solve both issues.