The best retrofit I've seen is in the Murphy's rig.
I have two portable burners. One is in the motorhome and the other at our house. I use them outdoors for hot, sizzle cooking of steaks, chops and fillets. I've abandon BBQs for a 10" Lodge cast iron pan.
I've never found a dominant brand. Each time I look, I see new brands. And, all seem to get pretty good reviews.