My ten pence worth - I'm sorry to say I could not get on with trackIR, I found it to be disorientating during driving and (for me at least) not very natural. However, it is a different story for aircraft sims, in those trackIR really works well, so not unusable, simply needs to be tailored.
I also had a three screen setup a while back, and went away from that too, and settled for one curved widescreen monitor. After a while I found that the two extra screens (for me) didn't add anything.
The biggest change I ever made was to get the Next Level V3 base for the seat, that really did make a huge difference for immersion. Expensive though.
But it goes to show, different people find different things work for them, so my suggestion would be to see if you can try out your proposed solution before you buy.
Hope this helps
Les