Why tho? That's inefficient when UAVs in future would be able to do it.
Until now, what we do know from non-official sources/estimations is that the H-20s (assuming only subsonic-capable) could have a maximum range of at least 10000-12000 kilometers. That means the effective combat range of the H-20s without refueling would only be somewhere in the 6000-7000 kilometer range at most.
The distances between PLAAF airbases located within China's interior and targets on CONUS would be at least 10000 kilometers, i.e. way beyond the expected combat ranges of the H-20s.
In order for the H-20s to be able to strike CONUS, there are 3 options:
1. Carrying ultra-long-range standoff (subsonic/supersonic/hypersonic) missiles with ranges of at least 4000 kilometers that would fill up the remaining gap between the maximum operating range of the H-20s and their targets; or
2. Mid-flight refueling of the H-20s - One refueling on their way to their targets, plus another refueling on their way back to their home bases in China; or
3. Combination of the above two.
YU-20 is surely a no-go for the PLAAF thanks to her not being designed with stealth capabilities in mind, which would definitely expose the YU-20s to immediate enemy detection and fire.
On the other hand, there are 3 major issues associated with aerial refueling UAVs like the MQ-25 Stingray for China's H-20:
1. China does not have air bases located across the Pacific to host them;
2. China does not have carriers that can operate deeper into the Pacific while still having sufficient cover and support from bases across the Pacific and from the Chinese mainland to host them;
3. Those UAVs would not carry enough fuel to refuel one H-20, let along a couple of them. If the UAVs are made larger in order to fully refuel the H-20s, the increasing size demanded of the UAV would render the need for aerial refueling UAVs rather pointless.
Therefore, alternative method of refueling the H-20s is required. But fitting individual H-20s with buddy refueling capabilities wouldn't do any better, since every H-20 involved only has rather limited onboard fuel for long-range strategic bombing runs.
Hence, it would be much better to have a specialized refueling variant of the H-20 (let's just call this variant HU-20). Compared to aerial refueling UAVs like the MQ-25, the HU-20s would have:
1. Much larger onboard carrying capacity for more fuel (~6 tons vs guesstimate 20-30 tons at the very least); and
2. Sufficient stealth capabilities to refuel the H-20s on their bombing runs without risking too much for the enemy to detect them.
The general idea for the HU-20 would be as follows:
1. The HU-20s takes off from their bases in China and join up with the H-20s on their way to their designated targets;
2. The HU-20s refuel the H-20s halfway of their journey;
3. Once the refueling are completed, the HU-20 turn around and return to their bases in China;
4. The H-20s continue towards their targets;
5. Once their bombing runs are completed, the H-20s turn around and return to their bases in China;
6. The HU-20s meet the H-20s halfway of their return journey and refuel the H-20s for the second time; and
7. The H-20s and HU-20s continue their return journey to their bases in China.
