These caches require a significant amount of work to get to. You will need a non-powered boat in the summer or walk on ice in the winter. These islands are surrounded by significant vegetation, getting a powered boat in there is going to be difficult!
For the big island, you may choose to land at one spot and hike the rest. There are lots of game trails that run around the island, you should have no problem with this approach. Remember to bring lots of water in this heat!
For our purposes, this is an island, even though it's not technically. You cannot access from land, as approaching from the NorthEast would be cutting through private property. Don't do that. The terrain rating reflects the need to access via water. The island itself is public property and you should feel comfortable searching for a cache here.
Remember, these caches are in potentially dangerous locations and seeking them is done at your own risk! There is no such thing as safe ice in the winter and you should take standard boating precautions. Getting through the reeds is going to be difficult, hard work! Maybe you can find where I landed?
The hides aren't difficult, you don't need any tools or climbing. I like hard-to-get-to, easy-to-find, so these should qualify. However, shorter folks may want to bring a portable step stool just in case! Don't say I didn't warn you! All of these should be about 6 feet high.