Both Polymer and PolyMc provide APIs to allow mod authors to make their mods work entirely server-side. With Totally Lit only registering a few blocks and items, and mixins (which can work entirely server-side), it might be possible for Totally Lit to support server-side entirely when either of these mods are installed.
Unfortunately after some research, it wouldn't be possible to add support for PolyMc given the current design of my mod. However, Polymer is still up for exploring.
Both Polymer and PolyMc provide APIs to allow mod authors to make their mods work entirely server-side. With Totally Lit only registering a few blocks and items, and mixins (which can work entirely server-side), it might be possible for Totally Lit to support server-side entirely when either of these mods are installed.