Calling all vapor barrier experts!

I have a question about the suitability of putting a 1 inch layer of Thermax/Tuff-R/whatever manufacturer calls it, on the interior face of the SIP walls of the house I’m slowly completing.

I need to space the drywall inward to accomodate wiring that will be on the inside face of the SIP wall, so I figured I’d upgrade the R value with the spacer and kill two birds with one stone, adding a radiant layer and a vapor barrier. Cost of heating went way up since I started this project, so this upgrade seemed like a good idea. 

Can anyone out there imagine any possible negative consequences to this setup? I know there’s debate about vapor barriers but this seems harmless. Would unfaced insulation make more sense?

Any help would be greatly appreciated.

Thanks,

Nick