I spend years telling people that waterslides weren’t appropriate to use on vehicles. Thanksgiving 2014 we put both waterslides and vinyls on my brother’s car. When he came back out for Christmas, he had already removed the vinyls but the waterslides were still there. He had removed the vinyls because they had started to gather dust along the edges of the vinyls. He wanted to remove the waterslides and reapply a different design of his own choosing since he is not a lover of vintage pinup art. It took us about 15 minutes of a hot soapy washcloth to get the decals to loosen, most of it was then removable however we did have to take the edge of a credit card to some of it.
We reapplied the decals of his choice and they are still going strong a year and a half later… Please see pictures he sent me about 3 weeks ago at my request. We live in California and the vehicle is NOT garaged.
The advantage to the waterslides is that they are thinner and leave less of a lip around the image… That and the fact that they won’t gather dust. I think if the decals are applied correctly they should hold up much better than either the cling or the vinyl. Our little trick is a very clean surface and a drop of “Dawn” in the very warm water. Use a moist paper towel to press all the liquid from behind the decal and then follow that up with a dry paper towel.
It may be worth a try to apply a single decal first and see how that works for you. You can also get a bit more life out of the decal if you treat it with two LIGHT coats of Rustoleum clear-coat 2X (about 4 bucks a can) BEFORE trimming the decals and applying them. The Rustoleum has a UV protectant in it which will protect the decal against the sun for a longer period.
Most clear-coat products have some degree of acetone (similar to nail polish) which doesn’t get a long well with plastic. Since the waterslide decals are in fact a very thin piece of plastic, applying acetone will actually fry the decals. The key to applying Rustoleum to the decals is to initially apply very light coats. The clear-coat actually goes on as a mist and dries before it has time to do any damage. Once you have several coats of misted clear-coat, you should be good to go. The Rustoleum has a UV protectant in the formula that will help protect your decals from the harsh sun.
We have a lot of chopper shops that opt to embed the decals permanently into the finish of the vehicle. We generally recommend misting the decals prior to application to create a barrier between the decals and the clear-coat the shop will be using. Since we don’t know how their clear-coat will react with the decals, it is just better to be safe than sorry.