I was looking up the release notes for the 7.0U1C update and spotted this bit of good news.
"With ESXi 7.0 Update 1c, you can use the installer boot option
systemMediaSize to limit the size of system storage partitions on the boot media."
I remember this being a design consideration for the new stack that I was deploying at work. I needed to have more than 150GB for the boot media.
Considering that I have 512GB per host there, it probably doesn't make sense to use this new option...
but on my homelab with 24GB of RAM per host, or an embedded deployment in VMware workstation... this could save money and space.