I have a really ugly green Lowepro Minitrekker backpack (size of a normal backpack kids take to school) with a Hasselblad, 2backs, bunch of filters, 160mm, 80mm, plus film, plus a Leica M4, 50mm, 35mm, 90mm, cable release, light meter all crammed into it. That is my small travel kit.

If I really want to go light with medium format, I'll grab my Zeiss Ikonta 6x6 folder and a few rolls of film in my pocket.