I'd be cautious of the words "sun tolerant" though. To me this always says "this plant would really do better in the shade".
You're going to spend quite a bit for a Japanese Maple, and you want to put it where it has the best chance to look great, not just 'tolerate' its location. I think blazing afternoon sun would certainly make just about any Japanese Maple tree struggle.
Is there any space on the west side of the spot where you could plant another tree that would throw a little shade over it in the afternoon? Maybe a pergola?
How about one of the Black Lace Sambucus instead?
Elderberry (Sambucus nigra Black Lace™) They have very similar foliage, but might be more tolerant of the sun, and would also not be such a big investment. They also grow a lot faster, and can be pruned to look like a shrub or tree, to whatever size you want your feature to be. Japanese Maples are notoriously slow growers.
