Excellent advice that seems very practical. One thought about CO2 for electronic gear would be to buy dry ice from any large grocery store (here in the US). Place in a plastic bag that is loosely tied and set outdoors. Make sure your electronics are not directly touching the dry ice because it is very cold. Do not completely seal the plastic bag because the dry ice will "melt" and turn into CO2 gas (lots of gas). I would place the plastic bag inside a paper bag that is folded shut, in case your plastic bag pops. This would probably work for delicate clothing or souvenirs also.