Yes you can grow a Limelight hydrangea hedge in Zone 7 far North California @ 3,400ft on a west facing front. One in the cubby hole made by the stairs might get too large and annoying pretty quick. There are several Hydrangea paniculata cultivars, some shorter in height, to choose from that might be a better fit for the true dimensions of the planting space you have.

I agree with Christopher too. As long as there is a source of water, you keep them mulched and you do not let the soil dry out, you should be able to have a great hedge. Paniculatas are the most sun tolerant hydrangeas, they are winter hardy to zone 3 and some grow to the size of small trees. Limelight can get to 10-12 feet high but there is a smaller Little Lime that gets about half as high (it is a slow grower too) and a slightly smaller still paniculata called Bobo. Little Lime's blooms are not as pure white looking as Limelight so keep that in mind too. Any hydrangea will be most likely be deciduous, unless planted in Z10-12-ish; I am not sure if you want an evergreen in front of the house instead or not.

Thank you, the height to the bottom of the porch is easily 10 feet so a tall hedge is fine. My biggest worry is deer and gophers but I've been fighting them for years and have some ideas around that too. My biggest concern was facing West with shade in the a.m. and hot sun in the afternoon but it's rarely above 90 degrees. I'm excited to try Limelight this Spring! Any great sources to buy them at? Thank you for your responses:)

That sounds like mild summer temperatures, not enough to worry about. The leaves require some afternoon sun respite here when we hit daily 100F++ here but rare 90F temps is ok.

Sunlight info: I have noticed that more sunlight exposure causes the lime green initial color to turn white faster. The opposite is true; less sunlight causes the lime green color to last a "tad" longer than in more sun locations.