Here are my 2 cents. The solenoid was installed on how many motorhomes? How old is the current one? Don't reinvent the wheel unless you know what you are doing. Those solenoids are solid, reliable, do fail, are incredibly easy to troubleshoot and replace. I suspect yours may have bad contacts. Since they move internally you may have found a clean spot. That said it will not likely carry the current it is designed to carry now. Buy a new one. Then take the old one apart and look at the contacts. You will be surprised. If you take it apart carefully you can reassemble it and keep it for a spare.
As for current carrying capacity. They are capable of being used as a starter solenoid or a supply for wenches. It should easily handle 200 amps for short periods. This solenoid is probably your (auxiallary/emergency start) solenoid as well.
My business has installed thousands of these type over the past 35 years. Just a good piece of equipment.
Ok, thats my opinion.