I’ve had to put things in tanks bigger than the gap offered many a time. Just a lot of shimmying and you’ll get it in.
Speaking from experience, it’s not fun when the center brace goes…
as for the wood, just clean it well and put it in the tank. If you don’t mind waiting a few days-weeks, just let it float. It’ll develop a white cottony fungus that is harmless and bristle nose plecos do a good job of cleaning it up. I always clean and drop the wood right in.
most of the wood in here is manzanita. Some of it was recently added and literally just rinsed it down and went over it with a brush before plopping it in.
the manzanita sunk. It has some fuzzy stuff on it, but I am going to clean it off. I also need to scrape all the lichen off etc. I will take a pic of the center brace.