The real solution to all of this is this... if your DM is being stingy on sneaking up on monsters and stabbing them in the back... avoid making ANY melee rogues at all and just continually have ranged rogues firing bows out from behind cover, gaining Advantage and Sneak Attack often. You keep doing this over and over to the point where your DM gets so bored of that character concept that they end up coming on places like EN World to make the same tired "We need to nerf X because all my tables use X and it's so boring!" threads. (See the Great Weapon Master feat.) Then at THAT point you go to your DM and say "Look, if you want us to stop just using bow-firing rogues... then stop making it so hard for melee rogues to sneak up on monsters to stab them with Advantage and Sneak Attack just because you don't think it's 'realistic' to come out of the darkness and remain hidden!"
A "bored" DM is the best one to get changes made in your game. If they are going to be anal-retentive sticklers on what they think is the "right" way to play... then just play their way so hard and so often that they realize their "right" way to play can get very old very fast.