8" is too big IMO.
I Did a ghetto studio monitor with some ddc 6.5"s and vifa tweets. Sounded good but were not sealed, it was just the front panel.
Not sure I would use super tweeters for anything but keeping up with high spl.
Anyways, just play around with size and either make the design easy to take apart and shrink, or use polyfil to psuedo enlarge internal space
Go with sealed. Ported should be for the dedicated sub.
Mids n highs in sealed box = 70ish-20-30k. Sub = 18-whatever. I had a jl 10w3 in my room for htpc and movies really use that 20 range.
Bc2000d - jvf FI BL 15" - s800/4
offerup elite expert team 2016