No, Limelight is a very vigorous shrub that will easily exceed 8'.
Paniculatas are the most sun tolerant of the hydrangeas and might be the best choice for full day sun in your location. They are also quite winter hardy to Z3. Review the ones that indicate an estimated size close to what you are looking for. Examples of some of the most compact ones: Baby Lace, Little Lime (a more compact Limelight) Little Quickfire (a more compact version of Quickfire), Strawberry Sundae (a compact version of Vanilla Strawberry) and Bobo. While they are of similar characteristics (except for height/width) and bloom colors to their larger brothers, Little Lime has a bloom color that is like an 'off white' while Limelight blooms are more pure white. Or maybe I had too much to drink the day that I saw them. Hee hee hee.
Note: when buying Limelight and Little Lime, more sun makes the lime green color of the bloom last less. If you like the lime colored blooms, you can put them in more shade. I placed Little Lime in full but bright shade and the blooms have stayed lime green thru the Fall on some years (bypassing white).
Should you get one paniculata that at some point exceeds the height you want, feel free to prune it down. Best times are after it has bloomed but before it leafs out.
Most paniculatas will bloom on new wood. Depending on one's location, invisible flower bud production will begin sometime after leaf out, say from May to July-ish (varies based on where one is). Then the buds will open afterwards from May-September. I have seen the blooms start as early as May down here but you can expect to see them in the Summer months...
