I just went on a weeklong trip and brought along a Simpsons Classic 2 and a bowl of MWF. I've never seen the need for extreme smallness. The brush, smallish handle, but with a 24mm knot, fits nicely into a 20 Dram prescription bottle (vented) and the wooden bowl I have is wide but short. No problems fitting either of them into my toiletries bag. Including the razor, all of it took up less space than my old Braun facemower, and I got great shaves while I was out.
My travel kit - Muhle synthetic in their twisty plastic tube (if you want to get fancy, there are roll-up leather brush holders), a DE razor with some blades in a case, and a puck of Mike's or Stirling. I still haven't figured out how to use a shave stick.
I can only tell you what I enjoy, and let you judge for yourself. I use a Simpson Berkeley brush in best for travel (as well as in my rotation while at home). Great brush; big enough but not too big (oh, and I face lather). For soap I normally take either Klar Sport or Pre de Provence. Both come in a travel-handy metal tin with a screw-on cap. Sometimes I include a chunk of Klar Kabinett as a pseudo shave stick. Works very well.