With regards tonsoace considerations, if you are going with a 20m monoband the support system could be pretty simple.

My first portable antenna mast was a 20ft Shakespeare Wonderpole that can be had for not much over $20 and is very light.  You could support a sloper EFHW for 20m with that.  I often leave the top section collapsed (for greater rigidity) and set up a 40m EFHW in an inverted V with that very setup.

I also have a Jackite 33ft pole that could do a 20m EFHW as a straight vertical, but that is significantly more in cost, weight, and guying requirements.