In reality, assignments of in-hosue appariser(s) have to fall under the concept of dual control within the bank.

So I used black garbage bags and double bagged some of that mattress memory foam and shoved it up in in the hole on either side of the handle for the flue.  

If you are insulating from the inside, then closed cell spray foam is your best option - it will prevent the warm moist air in the basement from making contact with the cool walls in the summer.

I know that many working professionals in their 20's and 30's have no issue with it all.  

Actually, I used this particular type of raised foam paper for the 1st time about 8 years ago for my kitchen. 

I was online and googled it a couple weeks ago. 2 part do -it - yourself spray foam insulation was like 650 bucks for the two freon tank size canisters,,enough for a supposed 650 square feet.

Sand is one option but I have heard about a expanding foam that some epa approved company has.

I've never worked on mobile homes but on rental houses I go next size down and put in wood material (shims and small boards) to fill the gaps and create something solid to screw through the window into the frame, then fill the gap with spray foam and wrap over with aluminum.

The layer consists of cork or foam.

It can shave years off your path and maybe get you over the hump where you'd never make other wise and you'd just keep that day job.Given my role mentoring yellow letter programs and new folks in general, there's many gorillas in the room.