If you are an East Coaster, it's probably a safe bet to budget $4000 just for the trip alone.
Are you renting a camper to stay on the lake bed with your rig?
How many days do you plan on pre-running?
Where are you going to fine tune your Montero here?
How much racing experience do you have? Auto? 4x4?
Do you fully understand the safety requirements and costs involved?
Your posts talk about winning KOH (stock class), you are going against pro-drivers that will have $50,000 in mods done to a stock jeep or tacoma. They will have unlimited spare parts resources and unlimited pit crew knowledge. Can you compete with that? Or will you be a trail plug out of the gate?
In no way would I discourage you. I'm all about dreaming big and I say do it. Post up your build plan. Post up your sponsor search. Throw some pictures up here.
I have actually considered the same thing (KOH Stock Mod). I've been building on my rig for years and estimate it would still cost me another $9000 in parts/labor to get it in a position to run hard out there (not win, but just be able to be abused properly) and another $4k for the trip. Plus the 11 or 12 days needed for the travel/pre-running etc. Hard to commit that kind of cash to go run your car into the ground.
But then again, people say it is an experience of a lifetime. Look around, there are some guys on this forum who have raced in the KOH race- I would reach out to them for some help and advice.