You will get a newer nicer and likely larger TT for $12k.
Otherwise, take your normal household budget and redo it with an RV instead of a house/apartment. If you are in an apartment, remember to add a maintenance budget item.
While you can live cheaply in an RV, if you live the same way you lived before, there won't be a lot of savings.
Many campgrounds have wifi though the quality varies greatly. You will want a site with water, electric and sewer (or you can get a portable tank to dump your sewer. Long term stays most parks charge you per KWH. Heat & cooking is generally propane. If you are in a colder area, you can burn a lot.