I'm also an advocate for treating the series and the movies as separate entities in general, especially concerning interpretations of history and especially for that reason I do not treat ENT as canon.
However, ENT's "In A Mirror, Darkly" is set in the mirror universe where a lot of things are different and this is the one
exception where I can imagine it co-existing with TOS and leading up to events in "Mirror, Mirror".
Except for the Defiant's
aft torpedos I can't see any features of NCC-1764 depicted here that would contradict TOS canon (only some irregularities in the corridor design) and therefore have been grateful to "discover" new spaces in the engineering hull never seen before.
Just to consider such inspiration doesn't automatically imply one accepts the rest of ENT as canon. ENT merely added new visuals to a classic TOS design, nothing more but also nothing less.
As for my project it comes down to a simple question: Would Matt Jefferies have approved the ENT design additions to his Enterprise