Changed the oil again today at 9150 (2150 oil change interval), since Blackstone recommended keeping it down to 2K for now (I had to wait on parts to show up, hence the 150 over).
I also swapped in the Mocal 180 degree thermostatic sandwich plate. I didn't even end up using some of the adapters I thought I would. I attached the Mocal-recommended -8AN to 1/2" BSP Male:Male unions to the sandwich plate, and then screwed the -8AN 45 degree swivel ends of the hoses from the Stillen kit straight onto those. It was a little bit of a stretch to get the hoses to cover the extra 1.5" or so, but I had slack elsewhere in the hose routing so it fit fine once I shifted them around a little.
Oil change was 3 cans of 300V (so 6L, roughly 6.3qts) and came out just about perfect on the oil level afterward - but then again compared to a regular oil and filter change, I lost a little bit extra from the sandwich plate swap (the plate itself and the lines both drained a bit when disconnected, but I didn't intentionally try to flush anything out of the cooler/lines). On the other hand, I did this oil change on ramps instead of level, so I may have left extra in the bottom of the pan too
So I suspect when and if I ever have one of those "regular" oil+filter changes that doesn't involve other work, it will probably come out somewhere close to exactly 3 cans of 300V, we'll see.
I also switched to K&N's HP-1010 oil filter this time around. It's identical to the HP-1008 in every way, but longer, so you get more filter surface area out of it I would hope. Fits fine, even on top of a thermo sandwich plate, with plenty of headroom around it.
I've found a small leak along my new oil pan gasket (from when I put the spacer on). Either I didn't get the Ultra Grey on perfect, or didn't torque it perfectly, or perhaps I even slightly warped the pan's mating surface during removal, who knows. In either case the leak is so tiny you'd hardly notice it. Made an oil stain on the plastic undercover, and the oil level dropped about half the range of the L:H on the dipstick during 2150 miles.
So probably next oil change, given the paint stripping incident with the pan anyways, I'll just order a new pan to be extra sure and swap that on with some fresh Ultra Grey and give it another go. The spacer should stay in place anyways with its own Ultra Grey, so it will be much easier this time around than trying to get them both up there perfectly at the same time.
Also on the Veil Paint mishap around the headlights, I've decided to postpone fixing it even though I hate looking at it. I've got more projects coming up in the bumper area anyways (which could lead to more damage which might as well all be fixed at once), and there's always a chance I'll end up falling in love with some (aero/cooling-functional) aftermarket bumper replacement for that matter too. So I figure I'll wait it out a little before I call a paint guy.