I decided to put the pallet planter up against the wall after all. Here is what she looks like now:
Handy Hubby secured her to the wall with brackets. We took the top plank off and filled in with more compost and plants.
A few weeks in the sun and the plants have gone CRAZY. I have already used cuttings from these plants for other planters as well as taking a few out completely to make space. A few things need tweaking- but I suspect this will be ongoing, like a normal garden. I didn't realise the two plants with pink flowers were lined up one above the other. Might move one. And space some more out.