Green’s Dictionary of Slang

stowed adj.

also stowed out
[dial. stow, to fill up]

packed closely, very full.

[Scot] M. Munro Patter 65: stowed or stowed out Pronounced to rhyme with loud, this means, packed, absolutely filled with people.
[Scot]I. Welsh Trainspotting 116: The train’s still fuckin stowed, so they cunts ur fucked fir a seat.