I have been able to extend the beginning of the trip slightly!
11 Hong Kong
12
13 HK > bus and flight to Beijing
14 b
15 b
16 b
17 b
18 b (Jianko to Mitianyu hike)
19 BNG > early train to Huangshan
20 h
21 h (possibly day trip to Dali)
22 HSN > sleeper train (if available) to Xi'an
23 x
24 x
25 XN > sleeper train (if available) to ZJJ
26 z
27 z
28 ZJJ > afternoon flight to Chengdu
29 c
30 day trip to Leshan
1 Chengdu > flight to Guilin
2 Guilin > Thailand

I know there isn't much time at Chengdu, but that's quite intentional as the main appeal there for me is Leshan.