Any fan of the OSR knows that one of the cool things about our corner of the hobby is just how portable it is. Sure, you can just load up all the PDFs you want on a tablet, but most old schoolers prefer actual books in hand....
For example, my default "OSR Pack and Go" looks like this, depending on which flavor of RPG I feel like dabbling in:
One copy of the White Box Fantastical Medieval Adventures RPG
One copy of Beasties - Manual of Monsters (or insert other preferred monster book here; I like this one because it's digest format and has very cool, illustrated monsters Night Owl Worskshop style)
A copy of the White Box Omnibus (or alternatively White Box Gothic if you're looking for that)
One or both copies of Dyson's Delves (the best OSR dungeon resource hands down)
Those five books still take up half as much space as a single core rulebook for D&D or Pathfinder.
If I'm in the SF mood, then the adjustment is obvious and easy:
One copy of White Star Core Rules
One copy of the White Star Companion
Throw in a copy of the Hyperspace Messenger Compendium
Optionally you can add Between Star & Void and Tools of the Worldshapers
And just like as above, the five books for White Star still take up less space than Starfinder Core or Traveller core. Add in some dice, a notepad and pencil and you've got yourself a game!
What sort of OSR Surival Kits do you like to drag along? I could easily see one which covers The Black Hack (the most emminently portable OSR-derived game out there), or pretty much any of the Night Owl Workshop games (which are all utterly amazing). I've got a serious preference for digest books, and if I ever saw --say, Goblinoid Games-- produce a thick and portable version of Labyrinth Lord I'd totally snag that sucker.