One finds old, established and generally heavy flowering camellias in full sun all over in Seattle neighborhoods, much the same as one can find rhodies in similar situations. While it may not be the most ideal siting, if you have good, moisture retentive soil and pay attention to any summer irrigation, full sun can work. I'd be most attentive during the first couple of years of establishment.

PNW full sun conditions, even in midsummer, tend to be much less intense than they are elsewhere and you can typically get away with growing part shade plants in full sun here if appropriate care is given.

But in Portland you can add 10 degrees of summer heat over Seattle, and maybe more against a fence.

There's not enough sun or heat during camellia bloom season in Portland to hurt.

I recall quite a few sunburned rhodies in late summer here, but burned camellia leaves seem to be rarer.

I do put a small sprinkler near both of our camellias at least once a month in the summer.

Since many people here don't water enough - if at all - many of the Camellia japonica shrubs seen around in sunny positions have very poor foliage color. Frequently the north side of such specimens is green, where the plant is actually shading and protecting itself. And the flowers of examples so located tend to be regularly badly scorched as well, a problem with this shrub in frosty climates generally (we also have camellia petal blight in this area). For general garden purposes, particularly in a sunny position a Sasanqua camellia would be a better choice. These actually prefer a warm position in cool climates, and also tend to produce a looser more informal growth lending itself well to informal planting. Another bonus point goes to their flowers often being fragrant.

The various C. x williamsii cultivars are also much better landscaping subjects here than C. japonica, which particularly in the large-flowered forms prevalent at outlets really looks and performs as though it should be used mostly as a tubbed specimen under glass - indeed British references recommend it specifically as excellent for conservatories.