Can I do a border run to Cambodia after my visa-exempt status expires and return to Thailand on the same day?

My 30-day visa-exempt status expires on Thursday 22nd September (having already been extended once at the Immigration Office on the 24th August). I was slightly late when extending the first time (due to illness) so had to pay a fine.

My two questions are:

(i) am I able to perform a ‘border run’ to Cambodia, get stamped out of Thailand and then walk back across the border on the same day to begin a fresh visa-exempt cycle?

(ii) will it be an issue for the immigration officers at the border post that I was slightly late in extending previously?

Thanks in advance.