It will take a lot of liquid latex to cover that area and many, many coats. I did something like for a prop piece and I used a whole small bottle for the area equivalent to maybe one foot.
That might be an okay solution.
I like Indefatigable's idea that best - the best of both worlds. The good thing about a fabric piece is that it can easily be replaced if it wears out and won't ruin the costume in doing so.
Disclaimer : This post written by a Grumpy Old Man
Actually in the pipes:
- Remaking Ser Loras doublet.
- Luke Skywalker, A New Hope
- Wind Waker starter costume in swim material
Eventually: Paul from Dune, Faramir, Harry Sullivan