It doesn't work that way for mass troop movement. You clear the path ahead before moving large groups. The Russians would use crippling airstrikes to gain ground and then file in down the roads once it's safe setting up new forward areas until the next stretch is cleared via air, the same way we did in Iraq in 03. Straight up the poop shoot known as MSR Tampa from Kuwait to Baghdad in a couple of weeks. Air superiority cleared the way.
Even without the mud, terrain is way too difficult in the eastern Europe part of the world not to use roads for 95% of the way. Same as it was in WW2. Mountains, trees, rivers, cities, etc. The mud was a problem for the Germans invading Russia because the roads are unpaved and there were no other options. I have to imagine there are tons of paved roads in the Ukraine these days.
The desert of Southern Iraq doesn't have that problem. You guys were able to spread out as far as the horizon could see and drive straight ahead for days I imagine. If Russia invades the Ukraine, they will have to come right down the roads. And the artillery hanging around waiting on them better be dug in as hell considering the size and capabilities of Russia's Air Force... Infrared capable drones can spot a tick on a dog's *** from 50 miles away.**"
To your point, if there was a Desert Storm or WW2 style battle of armor/mech infantry on line in the fields, the muck would be a problem. I don't foresee that ever happening again though in major combat ops. The amount of change in tactics from when I joined in the late 90's to the mid 00's was massive.
Armor and artillery are still very valuable in the broad scope of combat, but I would imagine an artillery battery has a very short life expectancy trying to take on the Russian Air Force.
I don't disagree with what you're overall idea is. This would be the most significant global conflict Since Vietnam or Korea. But if Russia decides to go all in, it would be a rout in the conventional warfare unless NATO steps in. Similar to Desert Storm. Ukraine vs Russia in 2022 is not much different than Iraq vs US in 1991. Now we start talking about insurgency etc, that's a whole other ballgame. You can't win that **** for decades.
Ukraine has not been sitting back idle since the last time Russia did this. Most of thier modernization has been to the radar for their SAMs. It's not like Russia planes are going to go unabated. Ukraine does not need artillery. It is useless against moving tanks anyways. It would be a lucky shot. The best you could do is drop some WP hoping you catch the fuel drums on fire before they drop them. How ever artillery uses what is called, Shoot, move, Communicate. Russian will probably not know where it is. What Russia has to worry about is small man teams, dug in, camouflages with light armor defense weapons like our M19. England has sent a bunch of this stuff to them and the Canadians special forces are training them how to use it. It will not be a route. You act like Ukraine has no military. It is the third largest behind France and Russia. NATO has been aiding it for years now and they are defending not attacking. Attacking put's a lot of stress on military. Logistics alone is a pain in the ***. Now if I was a Ukrainian I would be more worried about my corrupt goverment making deals with the Russians.