This is something that I would think would apply to "sticks and bricks" (although we live in a mobile home with neither - lol) living as well. There are always unforeseen expenses in life, no matter where or how we live.
We live without a financial cushion. And every single need that we have had has been provided for. EVERY need. When we walk with Jesus every day, when we recognize that nothing we have is truly ours, but rather provided for our use in serving Him, and when we acknowledge that He is the source of all we need, He never fails to meet those needs. I cannot imagine that He would stop keeping His promise to take care of His children just because we would be living on the road rather than on a lot.
His love and care for us is endless, and as we live for Him, He provides for us. I can count on that as surely as I can count the fingers on my hands :).
God never fails.