Or a smaller log! LOL!

I need a bigger car

Why are you ending up with a 14” wide slab from a 36” wide log? What set up are you using that requires you to put those heavy thing under the router sled when they are green just to stack them? I am just lost trying to picture it. I set up on a log and put wood strips cut to the size of my kerf as i go. If you mill the whole log where you’re looking to dry it then it stacks itself as you cut that way. Im not usually that lucky though

I dry fungus and plant materials by putting them in my car over the summer. The temperature in a car on a hot summer day can easily reach 200 degrees F, and even a mild day can drive the temperature over 100F. It’s not a consistent heat, like a kiln, but it eliminates insect and other arthropod infestation. The fungi I usually dry are the very ones which cause heart-rot / dry rot; shelf mushrooms and woody conks. There is some chance that some species of fungi have spores that can protect themselves from the heat, but I’ve never given it a try; what I do know is that under normal conditions your finished wood would be subjected to, there wouldn’t be enough water to reactivate the spores

Of course, if your wood slabs are too long to fit in the car, it’s not a solution.

How did your project come out, Ben? I’m contemplating a similar technique in making a tool-storage stand out of a birch log, but the difference is that my log has a completely rotten core. No worries about checking during drying, it’s all soft at the core! But if the stand comes out well, it’ll be something I may want to replicate, and your project’s outcome is relevant to future partially-hollowed logs like the ones I’d be making.