Hoses , belts yeah but don't know anyone that carries heater hose as spare , silicone tape and or duct tape and metal repair putty , oils yes but if your carrying water anyway coolant may not be needed unless you're up in the high country .
Grease ,zip ties and wire also tyre repair kit and something to fix a leaking radiator .
Sometimes if you get carried away your spares can take up more room than your gear almost .
Making sure you get your 4by checked out thoroughly before the trip will help but the unexpected can sometimes happen for example my injector pump decided to leak in the middle of nowhere .
Heard many stories of air compressors failing but who carries spares or an extra pump , stick to the basics because you won't be far from help by the sound of it .