Gotcha. In that case, anywhere I’ve referred to an “overflow tank” then I meant reservoir.
I drove it around the block to try to get the fluid flowing again. With the water I added this morning, the level is still well within the fill line area. The water also mixed with some fluid left in the system, and judging by it’s green color, I’d guess I’m at a 75:25 water:antifreeze mix. I’m confident I can get to a shop without doing more damage…but I’ve got to wait until Tuesday.
I may try the splash guard again.