I found some tests (the patent application) in the web for an interferon beta stabilization solution NEARLY the same as the new Rebif formulation (with polaxamer 188 and L-methionine) compared with the old formulation with serum albumin.
The experiments were about aggregat formation, oxidized forms, bioidentity etc. at different temperatures (4°C, 25°C, 40°C). There was not much a difference between the old and the new formulation at 25°C.
This is why I ignore the new storage conditions and if there is no fridge I keep my Rebif at room temperature for short time periods... But I do not guarantee for anything!!! Maybe its risky.
I also have a "Frio" pocket for insulin which cools with evaporation. You just need water.
I hope that was helpful,