Anything attached to the house and in your climate will need to go 4' deep to avoid shifting from frost. Going down 8' should not be necessary. Two approaches - a 4' foundation wall or a concrete post down 4' with a lintel across each post. Under the lintels, put a thick layer of foam so that any frost heaves will compress the foam and not damage the wall. My personal preference would be the post and lintel system. This is a quick guide. Details will have to be worked out in consultation with the building licensing people in your area.

You absolutely, emphatically, undeniably should not use an LVT in an unheated sunroom. You should not and can not use LVT, DuraCeramic, Vinyl (Gluedown), Konecto, Cork, or anything that has a vinyl composition to it. Now, I will be honest..I would not be afraid to put down a fiber floor Vinyl loose layed (no Glue) with an over sized expansion gap covered loosely (not Pinched with either base or 1/4 round as if the fiberfloor would shrink and expand, you would probably still be ok and not be offended. Porcelain Tile will work for you..and increase your home value as opposed to any other viable choice. Carpet (and they make some nice products that are fairly fade proof) will work and be inexpensive also. It gets cold in Chi-town in the winter and hot in the summer.You do not want a wood either....and especially not a vinyl product unless you take a calculated risk with a floating fiber floor (and that would only be if the floor is under 12 wide).

wall across from xmas tree and 4 framed photos, it will be under a wall mounted tv that pulls out on an arm. We have a tv room so tv isnt the focus in here

Picture did not post.