You are proposing a project. Projects cost money and time. Before starting, you have some questions to answer.
How long do you expect to live in that dwelling?
Do you plan on improving and modifying it, or just using it as a temporary structure?
What are the downsides of doing nothing?
How much of an improvement over those downsides will the project create?
What structural issues and code/permit issues are involved?
How much money is reasonable to allocate for the project?
How durable will the project be?
What are the alternatives?
Can the project be reused or recycled?
"I sealed up the holes and bad areas, cool sealed the entire roof and used black tar sealer on the really bad spots. The roof is 95 percent good but I don't think it will hold up." NO roof "holds up." It is simply a matter of how long they go between failures.
If you have patched to where there are no current leaks, and none are likely to appear in the stress of a windstorm, you have likely bought from 1 to 3 years.
Now comes the part you don't want to hear. Single-wides are depreciating assets. No matter how much money you pour into that dwelling, you will NEVER increase its value to others. Re-read that ten times.
If you plan on living in it for five years or less, save your money and just patch as needed.
If you plan on living there for more than five years, a project begins to make sense, as it can reduce energy costs and partially pay for itself.
Before you go further though, I see other possible routes of failure.
1. It appears that the home is mounted on primitive pillars that have no footers. As they settle, the home will warp and develop leaks. Doors and windows will bind or break. You can attempt to keep up with the shifting by adding shims, but that is not a permanent solution.
2. It appears that the bellywrap and insulation underneath have been removed. If so, it needs to be replaced. Bellywrap and insulation prevent pipe freezes, protect the underside, make for warmer floors and less heating and cooling costs, and limit moisture problems.
3. There is no skirting. Skirting is not just cosmetic. It protects and limits temperature shifts, especially in colder weather.
4. I'm not seeing any tie-down straps. Those are needed for protection from strong winds. You don't want your home to "Fall down, go boom!"
IMO, those four defects have priority over a new roof, providing there are no current leaks.
IF I was going to re-roof and had limited funds, I would investigate sheet EPDM (pool liner) or roofing membranes. Bonding it to the existing roof and then painting it white could make an inexpensive flexible roof that would last for years.
An aside here on metal roofs. A nearby farmer built a beautiful big horse and hay shelter in his field, with a metal roof. It looked great for a year, and then a strong wind came along and lifted part of it off and twisted up about half of it. He repaired it as a much smaller structure with less wind resistance. He learned, albeit the hard way.
If I were to go the metal roof route, I would pay for someone to auger holes for and set (in concrete) at least eight telephone pole sized poles about a foot from the edges of the dwelling. The (heavy) perimeter to the roof would be bolted to the poles about a foot or two above the single-wide. The lower edge of a shed roof would face the prevailing winds, and have a gutter for rain collection. The roof itself would be attached as independent sections, with a two-foot bridge section between each 8 to 10 feet solid section. Those two-foot bridge sections would be designed to hinge open in strong winds by having only loose attachments on one side, thus minimizing pressure differentials between the top of the roof and bottom. That way, the strongest winds would only create limited and easily repairable damage.