I taught school for 34 years. There was a time when I could never recommend home schooling. Now I think with dedicated parents, it is possible and some students, particularly your younger daughter may thrive under the experience. My niece has two children similar to how you describe yours. Her younger daughter had fallen through the cracks in second grade and fell deeper by fourth grade. Her teachers became unresponsive to my niece. I encouraged her to homeschool her. My niece is brilliant herself and yet she thought she was no match for her daughter. It turned out differently when they could use the whole day to learn. Her grandmother takes her to help do baking, teaching her about following instructions (recipe) and using fractions, etc. She is doing very well now and is greatly encourage. Her successes outweigh her failures.
Traveling the U.S. would give ample opportunities to learn about each state, the geography, animals, terrain, etc., as well as civics lessons. You really can accomplish a day's learning much more quickly than a day in school. You can teach each according to her ability and don't take time out for announcements, passing periods, recess, etc. Most homeschoolers I know finish lessons up by noon and accomplish the same as traditional methods.
Truthfully, unless you are a special needs teacher, most of us know little about teaching students with learning disabilities. I felt totally inadequate in that department.
There is quite a network for homeschoolers actually and I think RVers homeschooling on the road have a presence on the net.
I say "go for it" and have a great time!
Dale