True cost to operate a DP

I’ve learned a lot here on the forum and will admit, as some things have been made clear others not so much.

Here’s what I know.
I’m going to buy a 40’ to 45’ DP with a bath and a half.
* I’m going to pay $100,000.00 or less for my first motorhome.
* I will have a professional motorhome checker-outer check the vehicle.
* I will ask you folks here on the forum for your reaction to the vehicle I have in mind. To find it the diesel engine has known issue with that year and other known problems.
* I will use the motorhome four to five months a year for summer travel.
* I will try to find someone who will purchase and then give the motorhome to me. Ok, so I've mentioned one thing I may not know?

Based on the above I will know;
What I’m paying for the motorhome.
What the insurance will cost.
What the fuel cost will be based on where I’m going.
I will reasonable know the price of oil, fluids, tires etc.
Can reasonably know my expenses for RV parks.

My question is “how much should I put aside to pay for what I don’t know about? A $$$ amount for the year for the unexpected costs!

I’ve read; all kinds of posts on this issue. Some say if you don’t have hundreds of thousands of dollars in a Swiss bank account don’t do it. And all the way to, don’t worry about anything-just jump in the motorhome and go!

So I figure that the answer is somewhere in-between. My question is where in-between?

Is anyone out there who can give me guidance on a dollar ($$$$) amount I should estimate as an annual budget for the unknown?

Thanks to all