Ventilation issue:::

You might be able to ventilate towards the floor... from the bottom of the container, air flowing into/outoff the space between the ground and the bottom of the container.

If the container is sitting solidly on top of the ground... hmmm... do some air openings to the top/top-sides of the container... then, those bix square holes, cover them up with "security"... Metal mesh... the floor made for catwalks inside factories... diamond-patterned...

I saw the link you provided for the insulation... looks good. Quite honestly, I'm not an expert nor do I have experience on insulation matters... But, so far, so good.

It's sounding good man!

Behind this 'metal mesh', you place your in/out air ducts, a/c condensers (hot side), fresh air intake... etc.

????

You own a construction company? Dude, you're set.