Let me start off by stating that this is what I trained for and have ground experience in.
I spent 15 years (2.5 active and the rest reserves) in a formation that specialises in amphib and heliborne ops. I was mainly doing Terminal Guidance (not quite TAG but similar) so I spent a lot of time doing small unit ops linking the bigger formations, often in the "opfor" rear area.
The above doesn't mean I'm right and you're not ... though I do struggle to wrap my head around your, to me, rather cavalier take on the above. I suppose there is always more than one way to skin a cat so I welcome your explanation of your POV.
Meantime, here's mine ...
I come from Singapore. It is no secret that our planning and training is an unstated focus on a conflict with Malaysia (even if just simply by virtue of it being the only "land" border we have).
Malaysia has a Volunteer Corp or Home Guard of almost 3 million members (less than 1% armed). Whatever their peacetime and other duties are, the one duty of theirs that is pertinent to this discussion and that my unit specifically takes into account is their role in wartime - which is to act as eyes and ears for the military in their rear area.
(remember the Taiwanese rich guy who wanted to privately fund training of 3million volunteers? people poo-poohed on that cos they approach it from the POV of trained and armed resistance but ... as a civilian ISR network?)
I can assure you that even if there is no electricity and fuel, ground level ISR provided by these volunteers is a factor you need to take into account. Do not for a moment think that their SOP does not take into account loss of modern comms. In this case, their intel may not be instant but it will still remain a present threat and you should never, never discount the ability of a patriot on a bicycle and his ability to bring grief, in the form of a military response onto you. (or a goatherd calling the local garrison onto a scud hunting patrol, but I digress)
I am also not debating the PLA's ability to achieve total, as in literally 100%, destruction of electricity, fuel and C3 except to state that one never gameplans success to be contingent on the above. You plan on the enemy having all of the above and then attempt to degrade them to increase chance of mission success. A plan reliant on total loss of fuel and C3 will be so totally screwed by even a single digit percentile retention of the above. The actual effect on the ground may be the same at the end but the direction of approach and mindset is vastly different.
It's also an open secret that the Singapore Armed Forces actually conducts training exercises in Taiwan. I have 3x2weeks of experience extensively walking the hinterlands of Southern Taiwan on military opex, the exact kind of areas you have any chance of an unobserved, helo insertion into.
And once on the ground in the hinterland, this is the kind of terrain your mini-ATV has to account for ...
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Yes, we don't go through the forest 24/7 but even if take backroads/firetrails, we have to be ready to melt 15m+ into the treeline with any hint of oncoming. I don't quite see any ATV getting deep enough (or quietly enough) into that to be unnoticed.
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and sometimes, like sometimes-too-often, you have to crossgrain the elevation #justbecause (eg, we have to bypass the village on that spur but still continue on the metal road) and it can get like this. Don't quite see any vehicles getting up/down the last slope. ...
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Again, this is from the perspective of a small unit, behind lines, striving to remain unobserved which like I said, I spent quite a bit of time doing, even in Taiwan. The above pics are all internet sourced pics of Taiwan. I can't exactly use my own pics taken during OPEX but #trustmebro, it's similar. My observation is that outside of the heavily settled coastal region, the interior of Taiwan gets very hilly, very undergrown, very fast. Shanmao may be a mountain cat but it'll definitely struggle a fair bit to go where the legs are going.
Time and place for everything mate, time and place.