I live in Key west
and have been to the Oceanside Marina. It's nice enough and I'm pretty sure you should be able to make it in with your draft
I keep my boat at Sunset Marina, which is on the Northside of KW (Gulf Side). It is a bit farther in than Oceanside, but is very nice, protected, and friendly with about 30% liveaboards. It has a small grocery store and very friendly staff. I also think it is much cheaper than Oceanside. It is also very convinient to the backcountry which is a great place to snorkel/fish, etc.