Hey! I'm a professional comedy writer (as professional as a comedy writer can get), as well as a creative and novel writer, which mean I get the pleasure of proofreading at least a dozen pages per day, (and might I say that my test scores show my English is perfect?) so I'm very proficient and effective when it comes to getting the seeds out of your watermelon.
Creative input? It's what I excel at! Especially if you're looking for a twig for humor, and if the commercial comes out a lot better, I always appreciate a bonus (since I'm not charging much for what I'm providing you with), but that's completely your call.
PM me and I could send you samples, until then, all the best! :)