I have been a type 1 diabetic for the past 28 years and been bike travelling for the majority of that.
Your project sounds good and would be welcomed by some who were concerned by insulin getting warm.
However, despite what it says on the information leaflets, modern insulins keep very well even out of a fridge.
I traveled for 3 months around north america in 1993, a lot of it in the hot southern part, with some pig produced insulatard (them were the days....!) and it didn't go off.
I did take particular care of it, to be fair. The main stash, I kept deep in the middle of my rucksack and only got it out when cool at night with my day to day stuff being kept somewhere easier to reach.
The modern genetically altered human insulins we all use today are much more robust than the natural varieties. They will last a lot longer at higher temperatures.
I didn't bother trying to protect my entire stock of insulin from heat when I was last in Moroc for a month and I had not prroblems.
However, that is me, others might take a different view.
I have heard of some type 1 travellers using a fridge. They became well known as "those people with a fridge on their motorcycle"!
I could think of better uses for it!!!