Class A motorhomes don't come with a spare either. The lug nuts are torqued to 450-500 and weight alone calls for backup!
What I have learned to do is get a good roadside assistance company. Start the generator and wait for help.
If I decide to tackle it myself I can use the hydraulic levelers and raise the tire so I can remove it then throw it in the back of my Jeep tow vehicle and head to nearest town for a replacement or repair. All I carry is a good lug wrench.
In all the years I have been owning motorhomes I have never had a flat. Alternator went out on one years ago and a fuel pump on another but never any flats. If you take care of your tires, check them for correct pressure before each day or use a TPMS like we do and exercise your motorhome once a month to keep the belts from breaking down by sitting in one place and check the date code and change tires every 4-5 years you will probably never need a spare. Also, if you hit curbs, potholes and road debris often you will shorten the tires life.
Think about it...most people who have blow outs never check the pressure, run old tires or install different brands and sizes on the vehicle.
So what if you do everything correctly and still have a flat? Save your back and call someone. Best money ever spent! That spare you bought will probably rot sitting in one of your bays taking up room and weight you could be using for important stuff like fishing gear and such. And you won't need a trip to the ER after you pull a groin trying to lift it!