Mcp, those are such cute pictures. I love chipmunks! I seriously don't think they'll chew a hole through your liner. Just a feeling, I've had them for years and not had any problem.
So cute! Careful, you may be the cause of chipmunk obesity 
I did that.
My daughter and I fed the darling things so much that they were lolling about, practically waddling like ducks. I do regret that, because they became easier prey for the resident feral cat. But their babies survived and I now feed them much more discreetly.
I also put drainage pipes in with the Hostas, so they can hide quickly when they need to (and they do). It's my repentance. Worked out well- the Hostas cover up the pipes, but the chipmunks know they're there.
I think that feral cat will be our next pet. Seems like it'll be the the only way to get him/her from killing.
