You'll get used to playing slap bass without a pick guard, it just takes some adjusting. My first bass had a pick guard so that's how I learned to play slap but my second bass didn't have one. It took some adjusting, but now I personally prefer not having a pick guard when I slap now that I'm used to it because more space between the body and the strings gives me a greater range of angles that I can attack the string from on my pop and therefore gives me a wider choice of tone in my pop. I wouldn't suggest going for a clear pick guard because honestly they can look hideous on a lot of basses and really should only be used as an actual pick guard and not as a technique crutch. Its better just to buckle down and learn to play the technique on any bass so that you aren't so severely limiting your choices next time you buy a new instrument.
