is ts-13 the only one that has this problem of melting decals?
you could try and do a couple of coats of ts-79 (semi gloss clear) build up a protective layer let it set and then go to the ts-13 over that. i havent tried this but it might work. it would work like a protective layer.
what ever you decide to do it would be a good idea to paint some scrap peaces you have laying around. i do this a lot, i have a few spare kits laying around that i bought more for parts than the kit it self. ill take the body prep and paint the exact same way that i plan to with whatever project that i am working on. as i do each step it lets me see how everything reacts with one and another. i have saved a lot of models by doing it like this.
try this and if you have some spare decals as well you could lay those down and you can try doing a ts-79 in between the decal and the ts-13.
hope this helps. good luck