Lord knows I'm the Queen of the Extension cord, so don't let that hold you back! ;o) You could get a 100 foot one and bury it a couple of inches and nobody would ever know. Do you have an exterior GFCI you could plug it into?
Well, it wouldn’t be the first extension cord... my barn is still powered by an extension cord, since last winter, if you recall... ;~). So it’s not that it would upset the fancy landscaping around here ;~)
There isn’t a good outside GFCI outlet though... none of the outlets in this old house are, not even the ones in the bathroom ;~\
I’d have to run it out a window, which is fine for summer.