For the insulin cooling you don't have to go with a huge food fridge. There are plenty of dedicated portable electric coolers available on the market. Including battery operated and 12V ones, suitable for solar power (no need for a whopping 300W of power, something like 20W should do just fine for them); e.g.: http://sell.lulusoso.com/selling-leads/2...s-supplies.html

Regarding the ice bottles method - I understand the versatility of having clean water at the end of the melting phase, however the special gel cooling packs are noticeably more efficient in my experience (keeps it cool longer, occupies less space).

By the way, if using ice bottles - boil the tap water first, let it cool down, fill your bottles and let them stay for an hour or two open before freezing them. That way you will get rid of air and other gases in the tap water, as well as settle any solids in it. That will make you a crystal clear ice, which melts longer.