Question on frequencies

With that much seperation between your sub and your woofers this could end up sounding really weird, so you need to make sure the sub plays only non-directional low bass. Normally I'd say lowpass your sub at the standard 80Hz, but with this kind of setup you'll want to go lower so it is only active for very low non-directional rumble and is sufficiently cut up in the directional range.  I suggest using a low-pass on the sub at around 60Hz, and a band-pass on the 10's between 60Hz and wherever you are high-passing the components, say about 250Hz.  Use at least a 2nd order crossover, 12db/octave.  Then high-pass your components and your rear speakers at the same frequency (250Hz) and be sure you are using the supplied crossovers with your components.

You're planning on using just the crossovers built into the amps?  Hmm, well this could create a problem. 

With both woofers playing the same frequencies from different locations and from different amps you could end up losing bass not gaining.  About the best you could do is try setting the Memphis LP to 50-60Hz and the JBL LP to whatever frequency your HP for the components is set to.  But you now have the perfect setup for cancallation in the frequencies where the sub kicks in below 50-60Hz.  A better solution would be to get an external crossover like an Audio Control 4XS so you can actually create a bandpass filter for your 10's.

Complex setups like this require the correct control equipment, I'm afraid.  And it just gets more expensive all the time!