@clavius I am not a 450 owner, but I have installed VHF/AIS/Electronics on boats (and planes a time long ago). The difficulty in "snaking" the vhf antenna in part depends on the coax you choose. Some is more bendable than others.
You do not need to move the VHF radio, you can locate the AIS unit in a nondescript location as it really does not depend on the VHF radio. Which unit are you considering? I chose the Vesper XB8000. It interfaces using my SeatalkNG backbone and WiFi. Can be connected to a powered splitter which you can locate near your current VHF radio if desired or just about anywhere. You can also have 2 antennas one for the radio and one for the AIS.
Additionally there are now combined AIS/VHF radios. Some are receive only, others are receive and transmit.