Let bodies stay around for more than 5 seconds and let ships leave a wreck in space.
heck, they could even stay for as long as you're there... as an episode only lasts at most 15-20 minutes or so
(for persistent systems like the tutorial or the fleet encounters you could have the bodies disappear with the reset).
Think about it... you and your friends have been fighting enemies constantly for what seems like an eternity (but in actuality is only about 10 minutes) ... you finally go out of red alert and view the carnage you've wrought.
the ground is littered with bodies... or the space is filled with the wrecks of your victims, like an asteroid field of death (ah, right.. the wrecks probably should be pass-through-able also)
and yeah, I'd have no problem with it being a slider-option. it usually is in most games after all, and it would/should have no impact on gameplay mechanics since you would walk through a body, and fly through a wreck (applying physics to them would only become annoying).