New or used, large or small, any RV is a perpetual money pit and a perpetual handy man's dream come true. If you have both a solid revenue stream and mechanical skills with the equipment to match, then an RV is a nice choice. You have an instant house with everything contained in it, no waiting, it's ready to go. But, an RV, even one that sits stationary long term will need constant attention in order to maintain it.
Building a shed conversion may be just as daunting or even worse. But, (as stated above in the prior post), when building, you control everything and you know where and how everything is built. Based on your two choices, you'll have better use of space in an RV, unless you are very crafty at building construction.
You said you have done 2 bus conversions. That is a good asset for you with either choice. You have mechanical skills.
Being in Wyoming, winters can be brutal cold. Insulating will be your biggest challenge and keeping plumbing, sewer and fresh water, lines from freezing will too.
I have a Montana High Country Front Living and absolutely love the floor plan. And we use our camper year round. We do travel between Indiana (our home), Louisiana where I do camp hosting about 8 months out of the year, and North Carolina where I do another camp host a month or two out of the year. But, we've done our share win Winter camping in near zero degree weather. And when the temps get that low, the furnace must be running to keep the underbelly of the camper warm and keep all those pipes and drains from freezing. We easily burn through a 30 pound tank of propane tank in 2 days or less. That can get costly. And we still supplement with electric heat. But, that furnace MUST be kept running to keep the underbelly warm. Tank heaters must be turned on, and water hoses and sewer hoses disconnected and drained or they will freeze up.
Winter camping (RV use) becomes a totally different animal than Summer (warm weather) use. If the camper is not being used over the winter, winterizing is a must. It's not a big deal to winterize after you've done it the first time. If the camper is going to be shut down over the cold weather months, then all liquids, foods, everything needs to be removed so freezing containers won't break when contents turn to ice.
You will have the same problems and challenges with a stick-n-brick build too in the winter. Plus you'll no doubt want some type of air conditioning in the hot months.
You say you'll have water, electric, and sewer. If you do a shed build, where are you planning on doing this? Location is everything, zoning, and different local laws vary. If a camper is your final choice, will it be on private property or a campground? Either way, are you calculating in the cost of rent for a campsite, or the cost to rent a space to do the shed build? Campground sites do cost and they are not necessarily a cheap way to live. If purchasing your own private property, is it developed with the infastructure or are you going to have to have it all installed yourself. The cost of sewer (septic tank system or hooking into a city sewer system, installing electric, and getting water (drilling a well or connecting to city water) will cost thousands and thousands of dollars if the infastructure does not already exit.
Hopefully, you have all this calculated out ahead. If you are planning on living "off grid", you'll need to invest in a solar system for electricity, figure out how to get water, and what to do with "toilet" waste.
My opinion is different than Mikendebbie (above), I'd pick the Fifth Wheel. But ... I would not pick a travel trailer / fifth wheel ... I'd pick a "park model" designed for full time living and built to be stationary. Consider a park model.
BUT ... if you don't mind taking a trip to Minnesota, you might even consider purchasing an "ice house" RV. They are designed for extreme cold weather and ice fishing. Explore this option. You might be surprised.
Glacier Ice House - Click here.
Camping World article
Forest River Youtube video
