There isn't much to choose from in Dallas itself, so which side of Dallas you want to be needs to considered in the following suggestions. There are a few others, but we have no personal knowledge of them - - any of these should work with your description. You might check out Treetops, Dallas KOA, and Trader's Village in Arlington, Sandy Lake RV Resort in Carrolton, and Plantation Place in Sunnyvale/Mesquite. We have also stayed in Dallas HiHo in Glen Heights ...it has many long term and is rather run down, but we had a pleasant month stay. You should be able to find all of those via internet search.
Paul (KE5LXU) ...was fulltimin', now parttimin'
'03 Winnebago UA 40e / '05 Honda Odyssey toad