Hi Jessica,
I've used a similar approach but found that instead of using incognito mode, I simply have it so that the fields aren't cookied within the form. The only downside is that you have to select this for each form field, which can be time consuming but is worth it. Following the form submission, I have it stay on the same page. I've never had issues where incognito mode blocked form submissions; I've only experienced situtations where reps didn't fully utilize the form. 🙂
Another approach that can help is using the check-in iPad app, which is great for gathering basic information on booth traffic. We did a biforacted approach where the app was used for booth traffic and the form fill out was used for hot leads. The information on the leads was sent directly to the sales rep. Overall this worked better than the single form fill out.