Hey mate, wish i was in your shoes!!
Cruise craft have a 595 outsider with a lockable cabin. Enough room to sleep. Enough room to fish at the back. Can also walk around to the bow. Bit smaller than what you are after but something to consider. Think their tanks are 220L plus.
You have the signature 602 which you can get a lockable cabin. There is also a new signature 650 in the market. I have seen it in person, they look quite nice and heaps of room for fishing. Cant remember if it has a lockable cabin, but think you can get it.
The evo boats are good, ive seen them in person too. I personally dont like them that much. But personal opinion. If you do a search on evolution boat problems im sure you will read a horror story. But these guys fixed it all up from what I remember. But then again not everything comes out perfect. Im not bashing any brands here