I know where my fleet is, and I don't generally scatter my ships. If I forget, there's the Galaxy Map or even Ship Transfer in game for a quick reminder.
I can always look at my Materials and Data in game to see what I have and what I need for Engineering, and I keep the things I use on hand - except Tin and Tungsten - I'm always running out of those.
I've unlocked and bookmarked all the Engineers, and can always reference "View Engineers" from the right-hand panel in game if I forget. Tells me who, what, where, and what grade.
I have a list of Permits on the right-hand panel, and if I happen upon a new permit-locked system, I know either the system has no permit, or I know how to find out who controls that system, where they are, and making friends with factions is pretty simple - blow up their enemies, they like that.
I know how my ships are engineered and outfitted, but if I forget somehow, I can always look at their loadouts in the Shipyard in game.
Honestly, by and large, everything you might ever want to know is in the game somewhere - except for trade prices, and there's a really great website for that - though I often find Bookmarks and the Edit feature to be sufficient.
No spreadsheets required.