My recommendation is use long lease times in addition to static reservations.
Many years ago, I managed the network for and Engineering lab with several hundred PCs.
Our DHCP server was running Windows sever.
We set the DHCP lease time to sixty days.
Windows PC start trying to renew their lease at 50% of the expire time.
I don’t know if the Hdhomerun products try to renew before the lease expires.
Dnsmasq allows you to set lease the lease time.
Some consumer routers also allow you to set the lease time.
If you ever need to change subnets you will have force a DHCP update by power cycling the Hdhomerun devices.
If you know what you are doing you can use two or more DHCP servers.
Each DHCP server must have a different address range for each subnet.
All servers must have the same static reservations.
I run two DHCP servers using Dnsmasq on my home network.
Help and support for HDHomeRun DVR and HDHomeRun software for Windows 10, Mac, Android, XBox, etc.
I have done the other extreme - set the lease time to 60 seconds for testing HDHomeRun DHCP handling.
It does the same thing.