As regards "covert", the Feds better remain on the sunny side of Veridian III lest they become visible to the telescopes of the assorted Galileos of Veridian IV.
Which is exactly what they do in the scene where the three starships depart Veridian III, incidentally.
(That is, Data's earlier chart showed that Veridian IV would be on the same side of the sun as Veridian III during the events, so the sunny side of the latter would be the safe side. At other times, the dark side would of course beckon.)
Bright oddly moving dots on the sky have swayed world history before, here on Earth...
As regards removing the saucer by simply lifting it to space, the Defiant could more or less trivially lift the whole crashed Jem'Hadar bugship off a standard-gravity planet in "The Ship". Lifting the crashed E-D saucer should then be a breeze for the Nebula we saw, supposedly.
Timo Saloniemi