How do I "compromise" speaker placement

Rule of thumb - speakers placed well out into the room will excite less room modes. Keep away from side walls (at least three feet). Sit at around 40% or room length (do not sit with back against wall - very very bad) Subs are best well out into the room against the left or right wall about 3 feet in front of your mains. Try walking around the room while listening - the best positions or setup will have the broadest sweetspot and most even sound.

You will be surprised but rule of thumb works best - it won't give you that "jaw dropping" sound that you get when something is wrong and one note seems to rumble the whole room - so be careful - best setup is actually the most neutral and the least "sizzle" or "emphasis".

Finally use a PEQ or TACT or PARC to fix the worst of the room modes (notch down the "peaks" and leave the nulls alone and above all DO NOT aim for absolutely perfectly flat with thousands of filters - it often doesn't sound right at all - just "flatten" the bumps to with 3 to 6 db of the average and you may find it the most natural sounding - the lower you go in frequency towards 20 Hz the less relevant it becomes to get absolutely flat - flatish between 40 and 100 Hz is most important to achieve!!)

Not possible. 3 feet off the wall in a 11’2” width will have the mains less than 4 feet apart. The speakers are about a foot in width.

Well just do the best you can in terms of distance from side walls and also toe them inwards to reduce the magnitude of side wall reflections (effective once you get past about 40 degrees).

I agree with Bob;

1) Common sense - use rule of thumb configurations
2) Perform in room measurememts
3) Listen and decide what works best for you (usually a compromise is needed anyway as there is no "perfect position" for all aspects of the sound)

Why are measurements so useful - because it is very hard to be objective in listening tests and the most exciting engaging position may actually be the worst in terms of accuracy and ultimate musical clarity/enjoyment...the old boom boom tizz setup that most people fall for....impressive...wow I can really hear the bass...and the highs are scintillating ....sure but it is not musical cause you just downplayed the most important element the midrange...