Now that's restrictive.  I think I'd take advantage of that pole.  It's 
almost a quarter wave on 20 meters.  A half wave vertical, isn't dependant 
on ground radials.  I think an r-8 doesn't need to be guied.  If not, maybe 
an r-7.  You might have to sacrafice 80 and 160, because it'll be hard to 
put up more than one antenna. Best of luck!!!