Answer: I love the Crimson Queen Japanese maple, too. However Acer palmatum var. dissectum `Crimson Queen` is recommended for a location with filtered sun or at most full sun all morning long, so a spot with full sun all day would be too hot and sunny for this tree. These trees must have humusy, organic, acidic soil that is evenly moist yet well drained. They also need protection from winter winds. So unfortunately I don't think this is really the way to go. (It would also cover your entire space at maturity although it would be prohibitively expensive to purchase and move a tree that size - if you could find one.)
If you would like a small tree with a weeping form you might look into some of the smaller crabapple cultivars or possibly one of the smaller ornamental cherries. Both of these would do well in full sun all day and a well drained soil and grow relatively quickly.
Keep in mind that as it grows the tree will cast shade and the roots will take moisture and nutrients from the soil. For this reason it is usually recommended to grow a groundcover beneath the tree rather than try to grow flowers there.
To fill in the space until the tree grows you might use a bench set on a small, water permeable, cobble stoned or gravel area, another ornamental feature such as a birdbath or large stone, and just a few carefully selected shrubs.
In such a small space I would suggest using several specimens of one or maybe two types of shrub, perhaps an evergreen juniper or mugo pine for instance along with several purple foliaged barberries. If you use an organic mulch around all of the plants (as you should for their well being), you will then have a very low maintenance garden area.
Since you seem to have some specific ideas about how you would like your garden to look, you might want to consider hiring a professional garden designer to help you achieve the type of result you want -- some designers will do on site consultations at an hourly rate and this can be very helpful. Otherwise, your local nursery staff and/or county extension may be able to help you analyze the growing conditions where you want ot plant and identify plants that would thrive there with a low level of maintenance.
I hope this helps you start your planning.
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