Same here, and just for my touring kit, whose sizes and positioning haven't really changed in almost 30 years! I've been using a black rug for a few years, and it's 'spiked' with a silver paint pen.I used a fat sharpie marker to mark my rug. Nice and thick lines so I could see it easily. Sharpie doesn't fall off.
If you change setups, sharpies come in different colors.
This is the rug that i have and these are the velcro markers. The markers stay on the rug when you role it up and very easy to adjust as well. I use the round markers for the floor tom legs and the bass drum legs. The rest is to mark stands and pedals etc. The markers also work on the Rockbag rug i have too.That's pretty awesome! I'm going to go check that out!