Attack their supply lines. Burn anything not guarded. Force them to commit masses of troops to guard everything.
Plant real and fake mines along invasion routes. Use these sites as ambush locations to attack the Russians.
Prepare snipers to shoot and kill the Russians without getting caught.
Fight no pitched battles. Always escape.
Prepare to assist any Russian wanting to escape this rich man's war of Putin's and this poor man's fight. Help them escape to the West until the Putin's war ends. Treat them like Christians as long as they refuse to kill Ukrainians in the Ukraine.
Destroy bridges ahead of their advance.
Destroy and burn fuel points and ammunition with fires.
Make them pay a huge price in men and materiel.
Be aware of their fifth column. Treat them like spies.
I think your outline is realistic and even orcs of Mordor get it, that is why they are still festering near the border. But also, Ukrainian Army picked up the slack and won’t let them have it easily. Russians rely on overwhelming superiority, otherwise they are clumsy cowards, ready to play dead at any harsh sound.
We should recognize this. Pull NATO out of east Europe, and stop our 25 yr shad en war against the new democratic Russia just so the world can seize and plunder their resources.
Russia is pro family, anti abortion, pro christian, flat tax,etc. They are heading the right way, we're heading for the dumps. For the sake of future generations, the world needs Putin as a leader over the likes of Obama.
“My opinion is that any Russian invasion of Ukraine must lead to a protracted war using asymmetrical warfare.”
And that is a fantasy that simply is not going to happen. Crimea already proved that.