Janfe8027, we are very glad you are here and we want to be of any help we can to you and your family! If you keep a positive attitude it can be a fun adventure you all treasure for the rest of your lives!! After a divorce I moved into a Box van and my two sons came and stayed with me in it on the weekends. I think they remember fondly!
One of the biggest problems you will run into is heat and cold. Cold can be dealt with pretty easily but there is no good solution to heat. There are lots of tips to help but the best you can hope for is the inside temperature is the same as the outside. Can you live with that where you are?
What I would recommend for you is a Step van or a Box van. They are very stealthy in large parts of a city (but not at all in Residential areas), I lived in a box van for 6 years and never had a problem finding a place to sleep. It will be tight but I think they should give you enough room.
If you can afford it, you will all be happier by finding a cheap RV park to put it or an older RV in.
Bob