Adding salt to a marinade to brine? I have a marinade I really love for chicken that has a base of pineapple and lime juice, aromatics, and a little canola oil. There's no salt in the marinade and I don't season the chicken before putting it in either. I tried using this marinade overnight, but found that the flavor wasn't as intense. I think this could be solved by marinating for longer and/or adding some salt to essentially brine the chicken.
I know that a typical wet brine is around can be up to 20% salt, and this is what I'm thinking of doing for the marinade. However, I'm not sure if I'd ruin a big batch of chicken with this much salt. Given that it already has all of these ingredients, should I lower the salt content and marinade for longer, or just bite the bullet and go with the standard brine ratio?
Marinating is basically a surface treatment.  Marinades don't penetrate more than a millimeter or two.  Most flavor molecules are just too large. So, if you like the flavor after a short bath, just keep it at that.  A longer marination generally doesn't help.
Now, salt does penetrate, that is why brining works.  However, don't confuse brining with marination.  The added salt will not improve the effect of marination.  Only the salt will penetrate.
These are two different processes.