My mod is set to highest settings and has over 360 textures and 800mb+ of meshes. No memory crashes currently. If you know what you're doing, I'd recommend cloning your sins directory and go about gutting things the mod isn't using. Not being a developer of the mod, it might take you some time to figure that out, though. A good place to start is the textures for default ships, planets, and any skyboxes that might not be used. I've personally removed half the UI, the player portraits, most of the icons, and all research-related stuff. Meshes are more troublesome because unlike textures the game will crash if it can't find them. A way to bypass this would be to replace either the game or mod entity files for defaults to point to placeholder meshes and gut the ones you removed references to.
Since the game force loads everything in its directories, the problem with the ram limit for a TC is usually the TC + the default game, which the patches will make progressively worse.
I'd be interested to see how replacing default assets with 0kb placeholders in a mod works out in RAM usage, but only for the benefit of others, as I have no reason to hold onto the default assets myself.