I just attempted, and accomplished, the very same thing this week. The problem is the size of the room, of which I share, so small that even typical procedures won't work. So the secret is feather the light, turn it obliquely in relation to the subject, then add a grid to further limit light spill. Finally, a reflector opposing the feathered softbox, on the other side of the subject, fills the hard shadows created by the oblique placement. Adjust individual placement of objects, and exposure factors, to taste.
Thanks for the reply. Can you explain what you mean by feather the light and turn it obliquely in relations to the subject. Also, how did your pictures come out?
I'm not sure that the problem is the size of the room. I believe the problem is the octabox/softbox is too big. The size of the octabox/softbox is causing the light to spill over to the background, while a small off-camera flash can focus the light more-or-less at a single spot. See for example this video:
But someone with more experience with lighting can maybe chime in and give this newb (me) some help.
I'm also an (almost) complete studio lighting newbie, so I'm going to post my workflow and resulting images for you to see of this past week's test of my first lightbox, an Ezybox (clone) 60cm x 60cm, using a GN50 Olympus FL-50R flash with a Panasonic GX7 & Panasonic 12-35mm f/2.8.
The first setup was:

Setup of first shot. Dark gray trapezoid is Ezybox, sliver strip is a triangular hand-held collapsible reflector
The wall is one wall of the living room, the only wall (inconveniently) with color, in this case a middle-deep gold. The subject was standing about 5 feet in front of the wall, the Ezybox are in all the following cases set up about 1 foot higher than eye-level (that is, where the flash is located) with the box angled down so that the mid-line of the box was targeted to the eyes.
And here is the result of this very first setup

First setup results
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