You're right about the time it takes to pump out the cockpit. I did practice "self rescue" with my new boat. An electric bilge pump in deep or swift water would be a great advantage!
One thing I discovered about my new boat, is if water is shallow enough for me to stand, while boat inverted, lift the bow and cockpit is totally empty then do the re-entry. This technique is used in deep water too with a partner. Just means you're in the water a little longer. Beats pumping!
My previous more rec style boat had lots of room behind the seat, so this technique was not as effective, but love it for the sea kayak.
Re: where to put bilge pump, after practicing a few times, for me, the front deck worked best. Does not interfere with re-entry.