Most likely I'd be in a Spit IX. 15K is just below the alt where the IX looses power for a few K so the fight should go OK. Take it over 20K and I'd own them.
The last time I faced four K-4's (it was actually 6-7 K-4's) was in a scenario where I got caught alone in a Spit XIV at 25-30K. No one got any kills but it was nip and tuck for over 5 minutes before I spotted an opportunity to egress safely and rendezvoused with my scenario squad mates.