I have a Legend full aluminum 7x27 snowmobile trailer. It has Catch Covers in the floor and we use sleeves to slide down to the ice. I have an RV furnace in there, spray foam under the floor. Fully insulated. I mountain ride sleds so having the heat is nice for that. We have slept overnight in the ice with it fishing. It works, but the biggest drawbacks are it takes a ton of snow to bank it in. If you don't bank it the holes freeze fast. The other draw back is being so far above the water surface. You have to be right over the hole to see a bobber,which is hard on the neck. Landing bigger fish sucks.
I also tend to not go fishing as much, because of the hassle of unloading the sled gear, loading the ice fishing gear, then switching back. I don;t have a lot of free time, so I want to be able to just hook up the trailer and go when the opportunity arises.
I am in the process of designing a new Ice Castle and will leave the other trailer set up just for sledding and will use for early ice fishing with the wheeler and portable.