You can train some paniculatas into a standard (one trunk, trimmed lower branches) - is this what you are talking about?

There are some hydrangeas that get very large such as this one at the Atlanta Botanical Garden. Didn't even recognize it as a hydrangea for years until I saw it bloom. The only thing is it was not full of blooms - maybe because it was so large?

This far north, H. paniculata cultivars like Limelight appreciate full sun and get the most blooms with more than half a day of sun, but farther south the blooms last better with some shade.

The natural form of these hydrangeas is that of a large shrub, so with a tree form, you will want to remove any buds or small branches that try to grow along the "trunk" in order to maintain that growth pattern. If you want to see them not as "trees" find the thread on this forum about the Limelight hedge which has photos of the natural form.

Limelight has fairly stiff branches, and once the roots are established should be fine even in a windy area, though if it will experience high winds you might want to tie it loosely to a stake for the first year with a stretchy single figure 8 between the trunk and stake.