EHQS 12 s4 Quad Build Advice

I've had 4 EHQSS12 s4 drivers lying around for quite a while, so I think it's time to put them to work.

I am trying to get the most out of this build that I can (sound quality and output). I don't really have any limitations (size), other than I would like to use an amp that I already have rather than buying a new one, but if I thought it would make a big difference, I would consider getting a new one.

The amps I have include:

HK PA5800 5ch 110 wpc into 4 ohms
Samson S1000 500 wpc into 4 ohms
Behringer EP2500 (that I would rather use for a more serious build down the road).

I have read numerous EHQS12 threads, but most are using the s2 version. Having four s4's, I think that I am limited to either using 1 driver per channel, or all 4 drivers wired in series/parallel to achieve a nominal 4 ohm load.

So my questions are:

What have people determined to be the ideal enclosure volume for this driver? From what I can tell, most have determined a 3.5 to 4 cube ported enclosure with a 4" aeroport ~15" long to be relatively optimal for this driver, (tuned to 20-25 hz). If someone could advise me as to the optimum enclosure for these drivers, I would be eternally grateful. I would also be interested in slot porting the enclosure (if it made sense to do so).

Because neither of the first two amps listed are 2 ohm stable, I am leaning toward putting all four drivers in the same enclosure, and wiring them in series/parallel, and then using 1 ch of the Samson S1000 to power the drivers. This would yield 125 watts per driver vs. 110wpd if I were to use the HK PA5800 (one channel per driver).

I don't know if any of my logic is correct, so any advice as to enclosure size (for all four drivers), slot port size for the enclosure, and amplifier choice and configuration would be again greatly appreciated.

Best Regards,
DCartes