I had the same problem in my 1987 Bigfoot
fifth wheel. I bought a scratch & dent range on eBay. It has three burners and a working oven. Other than some minor flaws, it is new.
Although it only has three burners, they work much, much better that those on the original range. Water boils in maybe half the time. I'm happy as a clam with the new one and as a bonus, it has piezoelectric ignition. What a treat! (Manual light
Did the new range fit the hole? Well, not quite. There is a small gap behind (slightly noticeable) and a small gap below (not noticeable). This was a small price to pay for totally improved cooking experience.
I made a top for the new range because the flip up cover on the old range doesn't fit the new one.