What did you end up settling on regarding equipment, effects, EQ, etc., to get your acoustic sound, when you had the resources?
This doesn't answer your initial question directly, but I mostly ended up abandoning the idea of trying to emulate the sound of an acoustic guitar amp though my Helix. For me nothing beats a great sounding acoustic guitar through a well-positioned mic into the PA. However, the ease of use of my piezos through the Helix is what I have ended up playing for years now when I am not on electric. Consistent, predictable sound, no feedback, no bumping the mic with the guitar, no picking up random background stage noise. Also doesn't hurt that when I switch back to a Helix electric guitar preset, it mutes the acoustic by default.
Over the years I have tried various acoustic IRs and the Studio Tube Preamp and even the 'Jazz Rivet' (Roland Jazz Chorus) amp. Although I still select them now and then for a specific sound, I most often find myself dialing up my presets that omit preamps, amps, cabs and IRs and focus instead on getting the EQ, compression, chorus, reverb, & delay right. I always have a gain switch set up for solos; gotta have it for soling on acoustic with a full band. Going direct from the Helix has its advantages and gets a very respectable tone.