Do you have gobos? Even some heavy moving blankets and some c stands can make a decent make-shift gobo. Assuming the acoustic guitarist is sitting, you only need the gobos to be 4 feet tall at the most.

For a funk, blues or jazz bands I would say record as many instruments together and live as possible. For rock though, I would either do everything separate with a click or just have the drummer and bassist go together to get a nice natural rhythm section going. Then do the guitars separate. Think of the mix and recording as a band on stage performing to you. The horn section is together in their area. Normally when I record a horn section that is not a lead, I would record them all in the same room, 3-4 feet apart with their own mic. Then mixed i would pan each horn from each other but keep the whole section relative to their area. Like 60-40-20% left, maybe even tighter depending on the song and material.

Gobos are wonderful tools.
While not proper, I have four 4'x4' that I use regularly.

Here is an example of how I did a ska/reggae band w/ similar instrumentation:

Drums, bass, djembe, guitar, and keys all live together.
Here, I put the guitar amp in another room and used my gobos to make a box around the keyboard amp. Just throw a heavy carpet on top.

I overdubbed vocals, horns (sax and trumpet), and other oddities, but used the gobos again between the horn players' mics so they could play together, and still have some semblance of isolation to make use of in the mix.
(2 chairs + 1 gobo = taller gobo)

If you've got a few gobos, a little creativity in placement can go a long way.

Regarding the guitar, I would build a 3-sided box around him/her, and be prepared to overdub it if there's too much drum bleed in the guitar mic(s). At least this way you'll get clean drum tracks - and you might be able to use the guitar after all.

What are the dimensions of the room you'll be using?

Finally, like Brandon said, the sound you are going for will play a big role in how much isolation you need/want.