Had a chance to actually go back up to the local CDL store with a dozen pictures on my phone to have a chat. Everything I'm doing is what everyone else does..... When I brought up the fact that everything fits way better with 1/2" insulation he agreed 100% but stated that people buying this type of evaporator were on a budget and would likely balk at paying another $100-150 to get the 1/2", same heat rating, insulation. I completely disagreed and suggested that the reason people buy this small evaporator is because they only have 50-75 trees but want a professional grade (but smaller) evaporator to work on!! There is no question that we would have gladly paid that money for the 1/2" insulation to ensure "fit and finish".
I'm stuck for this spring but will likely rip everything out this summer once I get a reliable lead on where to get the proper 1/2" insulation. It's really too bad, this arch is so well engineered, crafted and assembled. Selling it with the 1" insulation really takes away from final product.
Oh well, as long as it makes steam we'll be happy.