HYPOTHETICALLY, if the soil were moist, would iris or marsh marigold thrive in 1/5-2" soil
yellow flag iris would grow great as should many other moisture loving plants many great plants can be grown on the edge of the bog lol
no---------- i mean: 1 to two INCHES of moist soil - i.e. on the edge of the bog liner which is shallow and separates the pond and bog so that hte bog doesnt cave in from the pressure of the pond water - thats why there is a wide and shallow barior which will be lined and soil covered
I feel that they would be top heavy and fall over on you. My Marsh marigolds grew to about 1.5 feet tall this summer. My water iris measured 3.5 feet. So.... to answer your question, it is probably not a good idea. However, you could put them into a large pot and place ON the liner. But they probably wouldn't survive the winter, at least not here in Canada.
You could try something like mysotis scorpiodes that is low growing with a shallow root system.