DDI on a budget

We currently have a single Windows DHCP server, AD servers as DNS servers and another Linux DHCP server for some networks. Windows part is hard to monitor, Linux DHCP has been taken down few times by someone directly editing the files and leaving a typo and then restarting the dhcpd and no one could get an address.

So I'm wondering what would be our options to do better DHCP/DNS/IPAM stuff without really paying in anything else than work hours. We have Linux guys we can borrow and of course students/interns we can "borrow" :) But we don't have the money to get Infoblox.

I'm hoping for a system where we could register a network/IP address/etc and that would automatically propage to DNS and DHCP servers, and the DHCP servers would be in a cluster. And we would have some sort of reporting who used what IP and where.

Netbox is probably the I in the DDI? And then dhcpd or should we go with Kea? Internal DNS should probably be at Active Directory servers as we have lot's of windows computers? We have FortiADCs for external DNS stuff I think they could handle the requests from the internet and we could do zone transfers to those.

Any experiences setting this kind of budget DDI? Or any tips what to do and what to avoid?

Thanks!