Flux core isn't more likely to warp body panels than any other form of welding. The warping will come from excess heat. It is possible to run a nice bead good equipment or 110v Eastwood mig/flux core welder. You mentioned flux core being dirty, the dirt or "flux" is how the wire is shielding the gas, that's why no c25 or 90/10 is required. Obviously just like stick welding the flux will need cleaned after the weld. Most people don't clean the flux or claim its dirty. Like it said previously if your having trouble welding flux you probably don't have enough experience mig/flux welding. You should be able to hear and see what you need to adjust to dial it in.