Fuel Filler Venting Issue

We just recently had a C4 Overland rear bumper installed on our 21 TRD Pro. They left the driver's rear wheel well access cover off (resulting the the fill and vent lines being exposed) and assured me it wasn't an issue. Today, I couldn't fill the gas tank without the pump shutting off every few seconds and having fuel spill over the fill neck. Did some research, and it led me to examine the filler neck area in the wheel well, and discovered the filler neck filter assembly completely encased in wet sand and road dirt (area circled in red). The picture was taken after removing the majority of the debris. We recently experienced some unseasonably warm weather where I'm at, so the roads are filthy due to all the ice and snow melting off.
Before I go back to the installer with yet another complaint, do you all think this could be the issue? We've never had this problem before.

 

Whether or not the freezing/thawing wet sand and salt caused the issue, I personally would want to have that area covered up. Nothing back there is capable of standing up to getting sand blasted and continually sprayed.

You’ll probably have to make something yourself since the stock plastic may not fit right with the new bumper. But I bet you could modify the factory plastic to fit.

 

Ok, so I'm curious...does installing this C4 bumper require removing those shields, or did the installation shop just remove them to save work and/or time?

 

I called C4 to ask that very question, and they said they don't ever remove it for installation purposes, and they don't know why it would be.
Additionally, I've got my winter tires on, which are only 33s, so I don't think there would have been tire clearance issues. That's one of the questions I'm going to ask the installer this week, and hope they still have that shield laying around so I can re-imstall it.

 

Same problem with my old Chevy Trailblazer, it's annoying. Someone told me it may come from filling the tank up to the last allowable drop of fuel, also dirt/dust buildup. I guess they(the vent/vent lines) can cleaned according to someone that had the same thing happen. I haven't attempted the cleaning thing. Any rate, you should get the cover put back when you prob. solved. Good luck. Tell us how it turns out.