When I run into something specific to the URL pramaters like this, I often use a QA/Debug audience that contains specific Marketing Cloud Visitor IDs including my own and any other individuals that will need to QA the experience. (If you are not sure how to get your MCVID I added instructions at the bottom of this post)
Here's what it looks like:

Then I do the following:
- I assign that audience to the activity.
- Set the audience allocation to 100% for the variation I am trying to QA.
- Activate the activity. (don't worry, only matching mboxMCGVID will get into the activity)
- Go load up the page with your query parameters and test out your exclusion rules.
Doing it this way you ensure that only the users with matching mboxMCGVID will get into the activity and you will no longet have to use the preview URLs with all of the predefined query parameters, you can use your own query parameters to test out the exclusions you have setup for your activity.
How to get your MCVID:
The easiest way is to open you inspector and throw the following into your console.
var myMCVID = visitor.getMarketingCloudVisitorID();
myMCVID
Another way to get your ID and even more information is to use the Adobe Platform Debugger found here.
Hope this helps!
- Chad