No problem flying VFR + FL100 in Germany, I do it all the time, like when I fly home from CZ and can’t get on top below FL100. All you need is a clearance, and away from the big hubs you always get it, at least I always did. I have the portable MH system in the Cirrus plus one O2D2. It is all you will need, and with the O2D2 even the small bottle lasts a long time if it’s for two...