Hi there!
I have designed an ISP from the stretch. I have a lot of very specific knowledge and skills on Linux, DNS, RADIUS, Provisioning, Monitoring, QoS, Proxying, carrier-grade networking, security and other stuff that may be interesting to you since you run WISP.
I am Mikrotik and Cisco certified. Furthermore, I am Cisco CCNP instructor. I will become Mikrotik certified instructor during the next month in Venice I hope.
Until recently I worked in a telecom company as CTO for 7+ years now. I am running a legal ICT company now. I can send you my full CV if you are interested.
Regarding your task, I can solve it with ease. I have a tons of experience and I would be more than happy to provide you with value.
Have a nice day!
Regards
Matija