Residency used to be a simple issue. Where was your home and where was your drivers license and cars registered. The answers you have received previously are from full timers and are tainted by there full timer experience. Many people own a home in more than one state and some even have cars registered in the primary residence and at their vacation home. The web site refers to the rules for registering your car. I do income taxes for a living and we have to deal with these issues all the time. The key consideration is where you chose to have your domicile as long as your actions do not contradict those stated intentions and you do not violate the laws of a state that could allow them to override your domicile intentions. Of course, why would they want to do that, solely to take money out of your pocket. No where in the laws is a permanent house the sole factor. In fact the state would interpret a full timers RV to be a permanent home because it exists permanently. Just cause it moves does not take away its permanency. The key term is your primary residence. This is defined as where you intend to return once you have stopped doing what you are doing. A college student, a student in a boarding school, a person, working over seas for many years, and a person in the military are perfect examples of how you can still claim domicile even if you are gone for extended periods. Of course your issue is the exact opposite, it is more beneficial for you to not be CO domiciled.
I checked the CO income tax rules and they say a person with a permanent home in CO who is in CO for more than 6 months (183 days in a calendar year) is a CO resident regardless of the persons intentions. You are a part year resident if you move in or move out of the state and intend to be a resident. A person who does not consider themselves to be of CO domicile is not a resident unless they break the rule above regarding the 183 days.
In today's complicated world the state will look to a series of issues to determine if they can force you to be a resident of their state. The primary items they focus on are car registration, drivers license, physical presence and voter registration. They will look at what address you used on your Federal 1040. They will also consider other actions like declaring domicile in a different state. In Florida there is a form that can be filed with the Secretary of State that declares the intention of a person to be a Florida resident which is additional ammunition to fight off the state. States have been known to get pretty aggressive and the burden of proof is on your part. You must document your stays out of state, you must document when you got your out of state license and cars registered.
In my opinion it boils down to how many days you are expecting to be in the state and what it is you want to do. And whether that matches up with state law. You can't want to not be a CO resident and stay in the state for 9 months. You could also be a SD resident for several years and then go back to CO because you circumstances change. Good luck and let us know what you decide. If you have additional questions just post them and I will get back to you when I revisit this forum.