Perhaps I remember someone else mentioning, having the same problem. I am very sure there is a workaround but I am not sure exactly to tell what.
From what I see quickly there are two other optional ways.
https://www.google.com/search?q=blender+raycast+ignore+backface
Option 1
added a small offset to the hit vector → used it as new origin for a second raycast
https://blender.stackexchange.com/questions/109539/how-to-ignore-backfaces-when-doing-a-raycast
Option 2
Maybe hiding them temporarily helps. → you hide it, cast the ray, unhide it
How to make the raycast ignore an object? - #7 by mano-wii
From what I see the least invasive technique is [2], if it works it would be really great. The other of option [1] looks like is very interesting, I don’t fully understand it though. If I am correct (based on what I understand) it means that if the normal looks points away from the camera (is backface) then you do a second raycast at this position. If I am correct, you do a recursive function call until you hit a face that points to the camera.
If both of these alternative ways fail, it means that you will have to revert back to the exact one you are in, that involves deleting faces. (Fingers crossed that [1] or [2] work better). 