I'd still submit it within the original deadline and make a point to mention that you get things done when you say you will.This morning we had a rather large quote due by Noon and the customer 10 days ago was insistent not to extend the deadline as it needs to get awarded ASAP. We worked out tails off to get this done. I've been up at 4:30 AM yesterday and today making sure that we got it all together.
Then, this morning 3 hours before the bid is due, we get a message that the deadline has been extended by 24 hours. I am so agitated right now, because our two other competitors could not get a quote done in time, yet we did. We followed the bid rules and they did not - so unethical IMHO!