Good funnel design. Crawl backs may be possible with certain devices with alot of climb / attachment potential.Those bats will be all over that device when returning to the roost site. A good education on bat return behavior is learned when watching bat responses to exclusion devices in the early morning hours.They will show you the good and bad of any device.
Couldnt agree more Bob ALOT can be learned by watching your own work in action. I did watches the first 5 times I used this system. No bats came more than a couple of inches away from the facia. The bats 'KNOW" where the entry point is they've used it for years, so why would they crawl AWAY from their "DOOR"? They Dont. I do like your idea of focusing air flow with luan, I think on larger gable vents I will try that in the future, with my wire horizontal tube. I dont claim to be an expert in anything, bat work included, but I am not a rookie and I would never post a pictorial of an unproven technique.