You'll need to keep your pipes wet (like in your house), but a simple degreaser emzine eater from any home depot type store will also clean the pipes. But it needs to stay moist and water run through it to flush and expand the emzines. Once they've eaten everything, they die, flush on down and pipes clean.
As stated above, never put grease down your drain (at home don't do it either).
We have never put grease down the drain in the camper (or at home). We always wipe the pots and pans, and even the dishes with paper towel first, to where the pan or plate is practically clean. Then use a good dishwashing liquid to clean the rest of it. Toss paper towel in the trash.
We never put food particles down the sink (especially in the camper.). We almost always wash outside, and any dishes that do get clean in the inside sink is usually just glasses and coffee cups at best. Even outside, we wipe with paper first.
Do we go through a lot of paper towel.... yep! But's that's easier to deal with than clogged pipes.