Here's an idea for a new show: SGC:CI

The counterintelligence department of the SGC, established after the events of The Serpent's Lair - people started noticing the two fireballs in the night sky and whatnot, so a counterintel department was established.

80% of their work is ensuring that Mulder never catches even a glimpse of what's going on. The remaining 20% is covering up things like the various spaceships landing (read: crashing) on Earth (such as the Bilisknr in Nemesis, or the various ha'taks SG-1 steals only to meet an early demise), and the space battles that are borderline impossible to miss, like the one over Antarctica. Or, Atlantis landing (sure the city is invisible but explain a sudden evaporation of the ocean surface and why there's a weird alien space city shaped hole in the ocean surface) and of course later taking off (they kinda need shields in space so at some point they'd switch over from cloaking to shields, making the Ass of Atlantis visible to the entire western seaboard).

The show would follow the SG-CI1 team who always remain in the shadows and use practical effect tricks like tripwires, Scooby Doo style traps and masks, and alien tech shenanigans. Like, Asgard holograms or the Tollan weapon disabling thingie. Imagine Mulder lining up a shot with a gun that shoots a GPS tracker dart, right into SG-1's van from one of the later seasons, only for a shadowy figure to appear from behind a tree, use the Tollan device, then disappear. That kinda stuff.