I guess this is a case where one doesn't ask....he just does it!
I have a 20 Meter Hi-Q Halo-type loop (6' dia) hanging from a tree
limb about 40' high. I needed lighter weight so I used RG-58 about
75' long....well-matched at the antenna for very little SWR.
I have been using this with 1 Kw SSB peak for about 10 years with
no problems...this includes reasonably long tune-up with full carrier.