Fuses, Circuit Breakers or nothing at all?

Fuses are like any other form of protection, a personal choice until required by law. Here's a point to ponder...
My daughter and I were roaming a pick and pull yard. She noticed that over 50 % of the wrecks suffered fire damage along with the body damage. I explained that this is due to electrical wiring being cut by the sheet metal. All the OEM fuses and carefully engineered harness routing didn't prevent electrical fires in a collision. The OEM wiring is protected from chemicals, chaffing, extreme heat, etc..
With the vibration present in a race car, wire chaffing should be a major concern. along with the heat issues and so on. Bottom line.. You will need to inspect the homemade electrical regularly whether protection is incorporated or not.