Not sure how using Russian bases is "a stretch too far", when you think about the flipside - The US would still have to use airbases in Canada, Australia and across the Pacific in order to get their bombers to China.
Besides, the case for striking Murican targets on mainland Murican soil is actually an appropriate response to US striking at Chinese targets on mainland Chinese soil. As long as China have the means to achieve it, I don't see anything wrong with it. The US can't keep on believing that only they can keep dishing out damages and not expecting retaliation.
In the meantime, Chinese SSNs with VLS tubes (093Bs) or VLS multipack cells (095s) certainly can do the same as the H-20s in terms of striking targets at Western CONUS.
However, compared to risking an SSN, which costs multi hundreds-of-millions, if not billions of dollars to procure and operate, taking years to build and prep for service, and only available in smaller numbers - Using the H-20s, which are often cheaper to build and operate, taking only months to build and prep for service, and are always available in larger numbers can better mitigate and distribute the risks and damages inflicted on Chinese warfighting units when conducting expeditionary strike missions as mentioned in the above post.