There are folks that do this. Just because it is a non-traditional lifestyle for a family does not mean it is not doable. There are definitely financial tradeoffs.
The moho is a depreciating asset and the money put into it will be spent money with no return. But so is renting. If you turn this into a learning experience for your children AND yourselves this can be money well spent.
$900 a month in RV park fees can be greatly reduced by staying a month in one place, boondocking on occasion, workcamping, state, federal, city, county, and COE parks.
It will get tight with two young children. And noisy. You will need to develop routines that can give each other alone time. Invest in a screen tent!
Things do break in a motorhome. Furnishings are chosen for being lightweight and not necessarily durability. Maintenance on a diesel is a lot more expensive than gas. But needs to be done a bit less. You should be able to budget $2-5 thousand a year for emergency funds while traveling. Hopefully this fund will carry forward for most years.
What is necessary, required to go ahead with this plan, is an exit strategy. What will you do and how will you live when it is time to leave this lifestyle? How will you afford it? What if catastrophe struck and you lost your motorhome and everything in it? A plan should be in place to address these situations should they occur.
And be or have a plan to get debt free. It is the best gift to give yourself.
If you've figured all this out and have health care, then go for it while you are still young. Life is an adventure.