oleschool OP
any distance from rear wall is fine
Ray, you want "some" bass loading so 1-2mts from the back wall. And side walls no closer than 1mt.
This is what I did in my room,
you have a 24ft long room so this is possible,I took out the centre wall between the speakers and left short walls behind the speakers, this still gave bass loading. The imaging is like you feel you can get up and walk into it and shake hands the the artists, and the depth of the image goes out into the backyard, I also get very good imaging outside the speakers.
Here is a crude drawing not to measurement/scale of the room.
https://ibb.co/LhGsmw6
oleschool OP Luckily my father in law is a drywallerOK very important, 2 x compressed R4" thick batts (we call them pink batts) (Rock wool batts even better) in-between the dry wall every dry wall you have you should do ceiling to floor. (we call them gyprock panelling walls.) This will stop hollow wall drumming. This makes the walls sound like they are made of solid brick
Cheers George