I was thinking of replacing mine with some PQN Boat Stereo Speakers, Spa25-4GYLD, but I've haven't had the time. I also don't know if they'll fit but if I try them out, I'll let you know. Below is the message I received from the manufacturer of the awning:
"Good morning and thank you for contacting LCI. The speaker is 2.6" and the front cover is 5.5 w x 7.875, and the back cover is 5.5" W x 10.380. If you have any additional questions please reach out to us at 574-537-8900. Thank you."