Living in an Rv can be economical. Traveling a lot in one, not so much so because of the cost of fuel, low fuel mileage of most large RVs and maintenance and repair costs. You will likely spend about the same on expenses such as food, clothing, entertainment, etc. living in an RV as you do now unless you make a decision to alter your live style. $900/month for site fees is high for many areas of the country (if you stay in the same place for a month}, but not all; so where you plan/need to be will affect that cost. You also need to realize that many RV park monthly rates do not include electricity so the actual cost will be higher than the one advertised. Local, state, and federal campgrounds are generally more economical for overnight or short term stays but generally do not offer monthly rates and may have stay limits of less than a month. If you are home schooling and your husband is running a business, work camping or volunteering to reduce site costs may not be a viable option depending on the duties and hours involved. Memberships like Thousand Trails will reduce costs only if they are where you want/need to be.
If your husband's internet business requires high speed and intensive data use, this may be a challenge. There are still many National Parks and other areas that do not provide WIFI and sometimes not even cellular coverage. Many RV parks struggle with providing adequate WIFI because of the huge data demand of streaming video and video downloads. Some, but not all RV parks are equiped to facilitate contracting with local cable or telephone companies for high speed internet access.
Medical insurance has been mentioned and how that will play out for itinerants(i.e. full time RVers) with the implementation of the new laws is yet to be seen.
There are many other variables such as income tax, vehicle insurance/registration, and sales tax that will depend on your specific situation.
Good Luck with whatever you decide!!!