Advice for new home theater room

[IM3CPO]

I am having a new home built and am looking for some advice on the dedicated theater room its going to have. As I am sure everyone here knows, no home builder takes these home theater rooms as seriously as they should and mine is no exception. I actually had them remove the wall sconces, etc., from the plans. I didn't even want them to install drywall (as I wanted to use purple) but apparently the house wont pass inspection if they don't install carpet, drywall, etc. so the minimum I could have them do is build a room with drywall and basic carpet installed. So- that is what I am starting with here...

The room is 18' x 13'. I would have liked to get it a little bigger, but that is as big as I could get. Ceilings are 10'. The existing drywall will be 5/8" and there will be insulation in all the walls and ceilings of this room. All the amps will have dedicated circuits. Entry to the room is from the back through an externally hung 3' solid wood barn door.

Here is a little diagram of the room:
https://imgur.com/a/RDn8HjH

(I couldn't seem to insert it as a picture)

My current equipment I can reuse is as follows:

2x JL Audio F-113's with sound anchor stands
3x McIntosh 601's (Center, and Fronts)
1x McIntosh 452 (for rear)
84" LG 4K TV (Wife insisted on this; this is leftover from other room we have)
Surround Processor: Datasat RS20i & McIntosh MX-151. Have both; can use whatever..

Front speakers: Sonus Faber Amati Futura's.
Center: Sonus Faber Amati Homage VOX
Rear Speakers: Sonus Faber Auditor Elipsa
*Not ideal, but these are left overs for when this used to be a different setup

I would like ideas from everyone as to how you would modify and configure this room for best acoustics and movie/TV enjoyment. Its only my wife and I, so we only need to fit 2 people. So I am not looking for equipment advice; I merely included some of the items as they affect the amount of space left in the room.

My initial plan was to implement a "room inside a room" but not sure I want to lose the amount of space I would lose if I did it within the whole room. I also don't necessarily have a budget. I want it to look and sound nice and be an enjoyable experience for technically as reasonably priced as possible but I could see spending as much as $25K - $30K+ if circumstances dictated.

What would you do/recommend?