Jake, My ITB MR2 is #22 so we definitely need to talk!
I have 15mm spacers on the car now with miata wheels (45mm offset, so 30 combined). I think 15 and the CR6 (20mm offset combined) will be too little offset for the fenders, but that might depend on your ride height.
the ones I use are made to bolt to the hub and have additional stud, but I knocked out the second set of studs and just use longer studs in the hubs and bolt it all together with the lugs (I do use the thin lugnuts to hold the spacer to the hub behind the wheel for ease of use). plenty of thread engagement with this setup. ARP studs for Lexus IS300 (PN 100-7715) fit the AW11 and are ~2" long when installed with rotors. twosRus.com usually has them in stock. not sure if the bolt-on spacer/bolt wheel to spacer setup will fit, I don't have a set of stock lug hubs with rotors handy, but it looks close. worst case you try it and convert to ARPs if it doesn't work.