Need help with my first full build and setting up active crossovers

[MrAcd]

So in my 87 mustang i am looking for some nice sound quality. so after a long time i went and bought a nice Clarion CZ702 planning the build out to be a 3-way active set up. I have subs and i bought 2 way JBL 3.5 mid range speakers to go in the dash and CDT HD-CF 6.5's for midbass in the doors. I have braced and deadened the entire door already. Anyways in looking to set it all up now and dont know where to start. Mainly what i mean is crossover wise. I have all the equipment installed already. Now im just waiting on my O-scope to come in to set gains on everything but my problem is i dont know how to set it all up HU wise.

I figured its really only two way active since the dash speakers aren't separate. I know i want my lpf for the subs

bandpass x-overs on my midbass

and hpf on the 2 ways.

another thing to add is the midbass have a dedicated amp so they are getting signal from RCA's while my 3.5's are getting signal and power from the HU(they where rated for like 20 rms)

So can i even set up active crossovers on speakers that are hooked up to the HU and speakers that getting signal from the RCA's?

This is the first time im trying something like this i just need a little guidance on where to start. Will this even work? were do i need to set my crossovers (just a base line) and are their things i need to fix or do first to make this work?