I honestly don't know, because I have not tried myself, so you might just want to stop
reading right here.
But from what I understand about the design philosophy of oVirt, it should be ok to change
it, while nobody probably ever tested it and everybody would tell you it's a bad idea
to do so, unless you're willing to rebuild from scratch.
The reason it *should* be ok is that the nodes don't care about the management
engine.
They care only about the information on the shared cluster storage.
How that gets there, who changes it: They couldn't care less.
Yet, I believe I have seen events being reported back to the management engine via REST
API calls, referring to the management engine via URIs that should have been using FQDN
only. So there is some biliateral communication going on, mostly asynchronous as far as I
can see and not using IPs.
What I can tell you, is that /etc/sysconfig/network-scripts/ifcfg-eth0 has
NM_CONTROLLED=no inside, so nmtui won't go near it. You can change that, delete the
line, edit the config... and hopefully it will live.
And in case things go seriously wrong, you should be able to fix it with hosted-engine
--console
But, again, I never tried it myself.
But I use DHCP on two out of four farms...