I would be concerned that the air flow past your vent would be disrupted by the low pressure created in the wheel well by the spinning tire. The higher pressure may try to enter the vent from the back. That would not be good. But you will still have some high pressure air entering between your work and the tire, maybe enough to generate flow out the vent.
Leave it for now and, if you want, I will loan you one of my pressure/flow gauges to try and analyze what's happening. You can test it as it is then tape it over to test it closed. I may even have a suitable spare gauge.
When you get the one side finished enough to test, the gauge would be very useful in getting an idea of what you have down the whole side so far. If changes need to be made, you can figure out what they are before starting the other side.
I would hate to see you make a cutout in the rear skirt. Do you think it would stay if you blocked the fiberglass out an inch or so from the hubcap and applied more resin/cloth? After trying that, I would consider flattening the hubcap a little at the center. It will be hidden anyway. You have a pretty nice aero shape going and, to my eyes, a cutout would spoil it. You are extending the rear skirt down to the bottom of your flare, are you not? Plan for what might happen if you have a 100% flat tire. Better now than later.
Be careful breathing all that stuff. Pretty mean on the respiratory system.
Working on a method to avoid cutting the rear skirt. Have been using a double cartridge filter mask, to protect my lungs. Fiberglass is some mean stuff. Thanks for the offer on the gauge CO. Had the tire contact the area that had to be filed. Other than that it drove well and seemed to coast easier down a 1 mile downgrade out of the grounds.
Thanks for all the positive post helps to keep the momentum up. Need to repair or replace my compressor, before doing much more. To Hot Today to do much.
The foam is construction grade 1" 4x8 sheet. Bought at the local mega mall. It was layered to the desired thickness with drywall screws to hold it together before the fiberglass was put on. Also remember to cover it with dura glass first, this keeps it from having chemical reaction. Why haven't a clue! Dura Glass is a fiberglass bondo, seems like it should eat it too. Lots of sanding with this method, but its a one off design. Could not see the point of making molds, which is time consuming too.
Hurt my back so things have slowed down. Got the compressor working today and lived through going to the gym. (losing weight in more than one way) So hopefully I'll get started. Plan is to do the left frt. fender and front end modifications, with air dam next. Here's hoping?
Time for a small update, gotta keep me moving. Took this week off but went back to work due to heat and most of all humidity. Can't get a handle on mixing hardners in this heat and humidity. Took two days for the glass to cure. Will begin to make up stiffiners for the new front fasica. Plus the hood needs to have some steel added after it's surgery. Found my air dam material sitting by the side of the road waiting for the garbage pickup! I love free!!!!!!