If you are going to use your motorhome primarily outside of your state of residence, and don't intend to store/garage your RV at your residence when you are not using it, a Montana LLC is a viable option. If you are going to park it in your driveway in Florida for months at a time, they are going to get you.
As others have said, if tax efficiency is your primary concern, you need to look at all the potential tax consequences. If you are retired and no longer earning a large income, income tax may not be your primary tax burden. Retirement can become a time of consumption, not income, and sales tax may be a bigger burden than state income tax. Property tax can also tax a considerably larger bite out of your funds than income taxes. You can research overall tax burden, state by state easily. But even that can be misleading, since taxes vary by each person's situation. For example, one of the most tax efficient places to live is Northwestern Wyoming. There is no state income tax, property taxes are low and you can avoid sales taxes by shopping in neighboring Montana. Housing costs are low, but there is very limited cultural opportunities and you are a long way form most anywhere. Life is always a series of compromises. Personally, I don't let taxes drive my life choices.
