Bring the brightest lens of the bunch; that's step number one.
You can shoot any ISO 100 film at 400 if you want, and you can do things like diluting Rodinal to 1+100 and slowing down agitation to something like 10s every five minutes, or even do standing development, but in snowy Sweden you might end up with really dull highlights if you do.
My advice would be to get a speed enhancing developer to process your film, after you return to your darkroom. Kodak Xtol, for example, which works really well for bringing out shadow detail. Diluted to something like 1+3 you also get very long developing times, which helps shadow detail.
If I were you I would be testing Efke 100 or APX 100 at 400, in similar lighting to what you expect to shoot in in Sweden, and then cut that roll in thirds and experiment with developing time. Your D76 might work really well for push processing too, if you dilute it enough.
Hopefully contrast will be fairly low in Sweden, which will help you, and something like EI 200 to 400 might be the correct exposure based on the lighting. If you'll be shooting in high contrast lighting, it might be really difficult to bring back some shadow detail.