Original Question Answer: You could do this and technically not have a lot of issues, however you would have to obviously implement this setup, it would only be accessible from one place (surrounding the AP) and you will add interference to the channels used by the AP. The amount of co-channel interference would depend on your current density of wireless coverage/ap's and whether you are broadcasting on 2.4ghz or 5ghz.
You could either go for an "onboarding" solution which does exactly this but with some further automation which various vendors offer. Or as the previous user has stated. have a captive portal which has either onboarding instructions.
I would also recommend that you put this on a separate VLAN and DHCP scope (as with an open network a lot of devices will autojoin and take your valid IP's) also implement some firewall rules to deny access to other LAN devices and make it non route-able etc.
In regards to the captive portal you can customise these usually so you could remove the login forms etc and just attach the data that you need.
Hope my post makes sense?