Hi, in case of interest to expand your service to your customer: I have a solution to inject ads into the browsing session. Can also, but not only, used with Mikrotik, as a proxy service.
Injection as interstetials or crawler, both as layered ads.
(Better solution compared to MTs interstetials, which will be disturbed sometimes, as they use simple redirection, which creates problems, in case redirection is done just during download of embedded objects for a page).
In case, you condiser using openwrt running on MT, I also have a captive portal with social login (g+, facebook, twitter).