I did not understand your setup exactly but if AIT5000 is indeed $1000 I'd pause right now. You have a million options, most of which will likely be better than the Digital Yacht and much cheaper.
I used to have their iAIS, bought it for WiFi, was not the right decision. Sold it on eBay and replaced it with my own setup, explained below.
First of all, if you have existing Raymarine Seatalk network, use E22158 (Raymarine Seatalk1 to Sea Talk-Ng Converter) to create SeatalkNG network (it is essentially NMEA2k). It only costs $85 and boom, you have an NMEA2k network with Seatalk NG connectors. Now you have options. E22158 comes as a kit, so you don't need anything else for this part, though you may want to have a backbone cable and additional connectors.
For AIS, you can get a transceiver for around $500-600k easily (Vesper Marine
XB-6000 or AMEC CAMINO-108 or the newer AMEC Widelink B600 for SOTDMA), add another $100 for WiFi (though I wouldn't, more below). All these will integrate with your NMEA2k network easily. BTW, don't buy an AIS without talking to Milltech Marine
(or at least looking at their website), they are the experts in AIS.
To get everything onto Raspberry Pi, just use this board: https://www.elektor.com/pican-2-can-...r-raspberry-pi
for 40 pounds. It will connect to your NMEA2k (assuming you don't want to send signals back, though I believe it can do it too), and to your Seatalk network via E22158. If you didn't buy a wireless AIS unit and want to make one now, you can do it on the Raspberry Pi for free. I developed a bunch of utilities to do this (https://github.com/itemir/rpi_boat_utils
). These are fairly straight forward but still requires you to know a bit about computers
and tech. If you don't care, spend a bit more and buy the wireless version out of the box.
If PiCAN2 does not work for you (too complicated or you need a proven bidrectional connector, look for an Actisense NGT-1-USB, more expensive but more robust).
All in all, you can have a new NMEA2k/SeatalkNG backbone, a good wifi transceiver (with SOTDMA if needed), integration with your Raspberry Pi and a wireless network, for less than $1,000. This is precisely my setup right now.