We have a good size garden, but because we live in a short growing climate, we decided to try to maximize our yields. We do square foot gardening on a larger scale and it's incredible the amount of produce we get. We aren't using raised beds as instructed in the book. We have just mounded up the beds. Make sure that you add compost to your beds every year.
It's very easy and you will also have to weed less often. A real bonus.
I like square foot gardening for certain things... Like a greens garden. It is great to just walk out the door a few paces, and cut fresh greens from living plants, instead of bothering with putting them in the crisper in the fridge.
A few of the main rules I have in my gardens, is to position the plants so I can keep my back straight while I work, avoid kneeling in damp soil, and maintain air circulation between plants.
Your layouts shown above are workable. If they were my plots, I might do several things differently...
First, I would choose a trellis that I can easily fit my hand through from the back side, so I could harvest beans from the north side.
Second, I would plant the pole beans in a row about 4-6 inches south of the trellis.
Third, I would probably put the squash together in one plot, and let them fight it out. Often squash will just continue to take as much space as they can, and will easily overshadow your lettuce. Another thing, is the squash stems are pretty abrasive, and will demolish tender lettuce on a windy day. Squash are also vulnerable to wind, due to the tremendous size of their leaves, so you might put them in the least windy spot.
Fourth, I might put the peppers on the southern most side of one plot, lettuce in the middle, and tomatoes on the north side of a plot. The further north on the continent you go, the less peppers plants will produce, and ensuring they get maximum sun, space and nutrients is important to make the best of the situation.
Fifth, I might leave a small space just south of the tomatoes, right in the center to aid in harvesting. While you might be able to reach two feet into the center of the plot, there will probably be tomato plant branches that get in the way of harvesting. You might not mind the first few weeks of harvest, but by the time it is September, you may not enjoy crawling and stretching for those tomatoes in the inside of the plot. A trellis that you can reach through easily, will be a big help, but probably not a magic bullet.
These are just my opinion. If you are set on this layout, it will still work. There are bound to be potential problems that only local people will be aware, due to climate and local pests.
Good luck, keep it fun and simple.