My viv looks more like yours and are easier to clean than you may think.
I put the snake in a secure holding container, and empty the viv. I let decor soak in a bucket of warm sudsy water (I use Dawn). I discard the old substrate and vacuum up any substrate I can't scoop out with my hands.
I wash down the tank, rinse, spray white vinegar to sanitize, rinse and dry with a micro fiber cloth. I rinse and sanitize the decor with vinegar, rinse, and pat it dry between clean towels. (I go back and forth between the viv and decor to give the vinegar some time to work on each item)
Then I put in new substrate and replace the decor. Any decor that is still wet is placed on clean towels to finish drying. I then put the snake back in and secure.
Except for any decor that needs to dry overnight, it's about an hour from start to finish to thoroughly clean the viv this way. The snake is fine without the stuff that is drying because I have plenty of plastic and resin stuff that the snake can use in the meantime. When dry I put the rest of the decor back. If you need to you can alway use temporary cardboard hides while stuff finishes drying.