Since I am no expert on this, let me first say what I have heard, and then you can correct me if needed.
I have heard that if someone age 55 or older retires from their employer, and is no longer a active employee, that they can cash out their 401k monies and only pay regular income tax on it, no 10% penalty.
I am somewhat aware of the rules concerning 72T.

Here is my question: I will retire with about 975K in my 401K account. I would like to put 900k in a IRA and draw a monthly income from those investments. With the other 75K, I would like to cash it out and after paying taxes, I would pay off my motorhome which would leave me basically debt free.
This would put me in a much better situation to ride out the 5 years of 72T that will have a locked in monthly amount.

Is it possible to do this?

I think your plan will work, assuming that you don't leave your job before age 55, and that this 401(k) is in the account associated with your current employment (i.e, not from some previous job). This also assumes that your particular plan allows withdrawals prior to age 59-1/2; while federal law allows this, your plan may have restrictions that could prevent it, so check with your administrator.