Also forgot to mention, this spot is shady until about 3 pm and then gets direct sun for the rest of the day. Is it too bright and hot for these plants?

It is really very difficult to significantly change soil pH on a long term basis. A raised bed, however, could work. Don't use any of the native alkaline soil. Instead, create a new planting medium on top of the existing soil. This does not have to be more than 8 inches or so deep. This will still require a lot of fill, so I would recommend pure aged softwood bark normally sold for mulching. This is sufficiently acid, relatively inexpensive and provides the good aeration and water holding qualities needed by rhododendrons. I've planted many rhododendrons in this and they do great. You might also consider putting down a layer of heavy duty landscape fabric before piling on the bark. This would prevent earthworms from bringing up the alkaline soil over time.
The proposed planting site is sort of the reverse of the ideal of morning sun and afternoon shade, but in a cool climate like yours, the afternoon sun should not be damaging and may be an advantage in winter as it would prevent bright sun at the time of day when leaves are most frozen. As long as the morning shade is not total dank gloom, rhododendrons should flourish.