Your antenna idea is good, and you had an easy-copy 20M signal to Colorado today when you were on W6/CC-072 (San Bruno Mtn).
If you only activate on one band, it's fine. I started out with a simple dipole for 20M, and it worked well on that band, but I quickly realized that I wanted to operate efficiently on several bands.
These days I often carry two antennas - both are end-fed. Both systems work well on many bands, and the total weight of both wires is only a few ounces. The antenna I use depends mostly on the space and supports available on the summit.
Wire 1: 66 feet of stranded #24 teflon wire, with a link at about 52 feet. No counterpoise.
A) EFHW on 40M - no counterpoise needed
B) EFFW on 20M - no CP
C) 3/2 Wave on 15M - no CP
D) Open the link at 52 feet - it's an EFFW on 17M - no CP
E) Open the link at 52 feet - it's close to EFHW on 30M - easy with my tuner - no CP
F) The entire 66 feet also tunes up nicely on 30M with my tuner, high-Z, reactive, no CP
Wire 2: 52 feet of stranded #24 teflon wire, with links at about 46 feet and 33 feet.
A short, convenient 12-foot #24 wire is used as a counterpoise with this antenna
A) Medium-Z resonant feed on 40M with CP
B) Low-Z resonant feed on 20M with CP
C) EFHW on 30M - high-Z - no CP needed
D) Open link at 46 feet - EFFW on 15M - high-Z, no CP needed
E) Open link at 33 feet - EFHW for 20M, high-Z, no CP needed
Many other useful band-tuning combinations are available with both antennas.
Over the years I've built and used many small tuners. My current favorite has taps and switches so I can efficiently match a variety of frequencies and impedances. The basic ideas are:
1) T106-6 powdered iron toroid core for best efficiency
2) Separate primary and secondary with taps on both
4) About 6-22 MHz
5) Two polyvaricon caps for input and output tuning
6) Dan Tayloe-type LED bridge for perfect nulls
7) 50 ohm input
8) Micro toggle switches for added C and L, tap selection
9) Multiple impedance outputs to mini-banana jacks
10) Matching range covers about 10 to 5000+ ohms resistive, plus a wide range of reactive matches - but not the whole Smith chart
11) 5 ounces
12) 4" X 2" X 1.5" - plastic case, aluminum panel
13) 2 feet of RG-316 coax to the radio
14) Handles 10W CW
15) I have a smaller version that weighs 3-1/2 ounces
16) T68-6 toroid
17) 3" X 2" X 1.5"
Using a tuner gives you maximum flexibility to cover various bands and use a variety of wires and counterpoises, while always getting full power and best efficiency from your radio. Tuners also provide added selectivity to permit operating along-side of other SOTA operators on different bands at the same time.
Once you "learn" your tuner and your wire, you can jump from band to band in a few seconds. You also can use an autotuner, or combine an autotuner with a manual tuner or step-up transformer designed to match high impedances. The idea is to get maximum performance from a few ounces of gear, while avoiding the inevitable losses of small coax cable.
It is important to get your wire as high as possible. While many contacts can be made with a low wire, better and easier contacts result when the wire is raised. I use an inexpensive telescoping fishing pole that gets my wire up to about 18 feet. I try to have the far end as high as possible, but on some alpine peaks, the far end may be only a couple of feet high.
In practice I see little difference in on-air performance between my two systems - usually I operate 40-30-20-17 meter CW. I look at my RBN spots afterwards. Over time any large differences would be apparent. Even some of the reactive matches I use seem to work really well, even without a counterpoise.
Please experiment, try various wires and tuning systems, always with the goal of getting more of your signal to radiate. The more bands you cover, the more chasers will follow!
If they hear you well, they will be waiting for you!
73 and CUL,