The HF Wiki thread (which is a sticky at the top of this forum) has a section for antennas - go check that out. Here are just a few possibilites (and notice, that some you would need a tuner, others not...)
a. From the Low Noise Recieve only loops site (Loops wiki), there's a simple little 50 foot long loop that oughta be right up your alley - built with coax, no less...
b. The Carpet Loop (found in both the Loops and HF antennas pages...)
c. Normally I wouldn't recommend an active antenna in a city, but this one is so unobtrusive, and it's an inexpensve kit (no less) you just might be able to sneak it into your patio - the North County Active Antenna (HF Antennas)
d. And of course, the PAR EF-SWL - now I know, you're thinking, I can't put that in here - you most certainly can - if you have an attic or crawspace, that might well be ideal. (HF Antennas)
I wouldn't go too overboard with antennas on this radio - if memory serves, like its R1000 brother, it's a bit sensitive to overloading.
By the way, the RadioIntel website shows a web page for the R2000- and there's a suprisingly active Yahoo group for it, too...
http://www.qsl.net/kc7bum/
Finally I'd consider sending it off to Kiwa and having better filters installed. Good selectivity is an important consideration on any receiver, much more so today then 20 years ago.
73s Mike