How to change the civil war factions' relationships?

Every time I go through the quest Season Unending, I think I have chosen the neutral route (I even followed a walkthrough on one occasion where the outcome was score 3-3), but after I finish the main quest, kill Alduin, and start clearing bandits from forts and so on, some are taken over by Imperials and I have to start making large detours in order not to kill them. I don’t want to play the Civil War questline, I just want both factions to treat me as neutral so I can pass through their forts and camps.

I have never killed a member of either faction. I have no civil war mods in my game. I don’t want to play the civil war.
Before Season Unending I can walk into any camps without any problems, but after Season Unending I am called 'Unblooded' by some of the Stormcloaks, and if I approach an Imperial camp they draw their swords and say things like "you're trespassing, get away or else" or words to that effect.

I have been informed by other players that after Season Unending they can still walk through any civil war faction’s camp and forts, but I can’t.

I was hoping for a console command to set things to neutral again, even if that changes who owns which city.

Solution 1:

After Season Unending, use the console commands player.addfac 2BF9A 0 and player.addfac 28849 0 to become neutral in regards to the Imperial Legion and Stormcloaks respectively.

Here are some gameplay tips for anyone who has not yet started Season Unending:

To assert remaining neutral during and after the quest it is paramount that you introduce the negotiations with the dialogue option "I have a message from the Greybeards".
If this option is missing when talking to either Ulfric or Tullius about brokering the treaty, the UESP suggests the following potential solution:

If you have not yet joined either the Imperial Legion or the Stormcloaks, and you have not talked to Ulfric and/or Tullius since Helgen, you will be forced to first talk to them about Helgen, at which point they will suggest that you join their side of the conflict. To proceed, simply finish and exit the first dialogue, then start a new discussion, at which point the option will appear.

User DrNewcenstein points out in one of the Steam threads that the only other option to request their presence at High Hrothgar is indeed to express your support for either faction:

When you get to Season Unending and approach either Ulfric or Tullius first, you're locked into a dialog option that says "I could have gone anywhere after Helgen, I came here to fight for <faction>". This essentially commits you to that faction.