My router fence has a safety shield that I don't always use, but it partially encloses the bit which will restore some of the air flow to the DC port behind the fence. The one shown is a Jessem and requires a fence with a T-track. Theoretically you could add an extension (Lexan) so you could keep the fence further away, or even a DC port through the shield, directly above the bit. As an alternative, you could make a shop built unit. It would not help with DCwhen cutting a stopped or full dado.
Here are a couple of sources
This one is tinted orange but is only $7: https://www.amazon.com/Router-Bit-Gu...09&s=hi&sr=1-7
A little smaller kind of yellow tint, about $6: https://www.amazon.com/Router-Bit-Gu...556582317&s=hi
JessEm's clear bit guard in the pix is available direct from the company, about $10: https://jessem.com/products/bit-guar...e-mast-r-fence
The more I do, the less I accomplish.