I currently run the pi-hole servers (yes, I run a pair) as DNS only. I previously used them for DHCP as well. It's no problem to set up and has the advantage that all the pi-hole logs will include the client host names rather than just the IP addresses. If you do run a pair, the "slave" can ask the master for hostnames too, so regardless of which pi-hole logs you are looking at, the hostnames will be available.
But my router's DHCP is permanently on, so to work around this, I had to narrow its range and then pre-assign those IPs to dummy hardware addresses. In the end I just switched off the pi-hole's DHCP and run my router's. But either works and it is not tricky to try, and not tricky to switch back.
As a suggestion, if your pi will be dedicated to pi-hole (a good idea in my opinion) an easy way to set it all up is to use
diet-pi as the base install image. This is a small Debian-based distribution, optimised for server boards, without any of the cruft often bloating other options. It also includes an option to install pi-hole when you are configuring it. Which makes it all very simple to setup and maintain.