I wanted better airflow, but clayrev's thing would have taken way too much time to print.
So, I hacked this together.
These spacers will separate the stock bottom plate from the printer's body by 14 millimeters, enough to clear the gantry's lower bar.
You'll need to print 8 spacers, total. Two should be the plain octagon version: these go on the side screws nearest to the gantry bar. The other 6 can be either type, but I recommend _wide. It's easier to hold onto while you install the screw.

UPDATE: I added/updated the SCAD file, it should be customizer-friendly.

Remove your bottom panel. Protip: take off two of the feet and you'll be able to slide it under the gantry bar without disassembling the entire printer.
Now, reinstall the panel with these spacers on the (longer) screws.

I don't have any easy way of measuring my printer's internal temperature before/after, but with these installed I feel like I'm hearing the power supply fan less often. I can definitely feel warm air wafting out of the airgap I've created, especially behind the printer.

OpenSCAD. The simpler part is basically a one-liner. This thing is so laughably simple that I debated even submitting it.