Karen,
You are on the right track! There is not stim that will work for everyone, some peopel will never make it out of the minimally conscious state. That is why there is no research backing it up, because it is nearly, if not entirely impossible to research. You can have 2 patients with the same area of injury and react in two opposite directions. You can't research it because there is no control group. (just an FYI I am currently working on research with TBIs and sensory integration), and have run into the great difficulties trying to set up a clean research protocol that will be valid.
What you are doing sounds very good. I have the best luck with automatic responses. Like ice on their cheek, to see if they turn away from it, ice in their hand to try to get them to drop it. Sounds that provide an automatic response like their personal cell phone, or a regular phone, family's voice, favorite music or TV show.
When you are working on vestibular, only try for one small component at a time. For instance, give them total body support, with them attempting head control, or using their arms for support. Don't have to them try to to mult-itask.
A log is the best way to go about it. I even have the nurses, RT, anyone who enters the room make a note on the log so I can see exactly how much stimulus the person is getting and to make sure it is not all at once (such as busy time in hospital is 6-7am) to see if some of that can be spread out to try to cover some ever hour during normal daylight times.
Another really important thing (in my opinion) is that during daylight hours, someone should open the windows shades (etc) for 15 minutes an hour or so, to help reset their circadian rhythm. After a TBI patients have extreme diffifulty with sleep/wake cycles. Of course during night time dark room, as close to night at home as they would normally have.
As far as outside resources go, there is not much. I have foudn it very helpful to boost my knowlede on sensory integration (specifically modulation disorders, but that is for further on down the road) If you have any SI therapists there they can be great help. Don't let them blow you off, I had issues with that. The SI therapist told me that it wouldn't work becuase SI only works for children who do not have an intact neuro system, well we now have an addule with a traumatically induced rewiring (non-intact) neuro system. Anyway I am getting tangential and diving into my personal research, so I will end with that. Please let me know if you have any more questions. You can e-mail me if that works better.
Em