I built an 8x8 that is 7' off the ground -had plans of framing up walls and such -the land was reportedly sold as soon as I had the platform built.

I made my mind up I wasn't going to try and make it 'perfect' -just get it close to square screw it off good and hunt out of it.
I used 4x4 treated [all materials treated] for the legs -I measured the width of a 2x6 down from the top and glued and screwed a 1' 2x4 at the corners for the 2x6 to sit on.

Screwed a 2x6 joist to the top of 2 4x4's dropped the 4x4 legs into a 1' deep hole I had dug -leveled them -packed dirt around to hold it upright.
Repeated that process by digging 2 more holes square to the standing 4x4 with 2x6 joist.
Then joined the 2 together -now all you have to do is add 3 more joist hangers/joists heave a 3/4" sheet of treated plywood -square it up -screw it down to joist .
You will have a couple of inch gap since non of the joist were cut -you'll need a 1x4 to fill the gap . NO lumber cutting -ALL full length 8' lumber and decking.
This took me 5hrs by myself -I was informed that evening the land had been sold and the future of the lease was unknown .
SO instead of building roof -walls and windows etc. like I had planned I used some odd shaped rolled edge 1x2" lumber - don't even know what it is used for but it is in the treated lumber area at lowes depot.
I screwed these 8' length 1x2" 'sticks' to the outside edge around the perimeter then used some over head and put an 8x8 camo tarp over it for a roof - then used camo tarp for walls and some screen to look/shoot through. Just staple the wall camo tarp on from inside the blind -I've used landscape weed barrior stuff too -CHEAP $5 a roll -just staple it from the inside.
About $250 in materials and 8 hrs of labor .
I just cobble it here and there when need be -I camp out in this shooting house for days at a time .
I have a cot/deeluxe pad -5gal. water dispenser -walmart sleeping bags [made in Alabama] -propane stove and can see and shoot from 3 directions 75 yds -210 yds and 300+ yds.