RNS is expensive and slow, it needs a hell of a machine, and a 3D accelerator card as well. Poor chart support. No 64 bit version, and I guess it will never be,
Raymarine has been bought by Flir in the meantime, this is what I think, I could be wrong.
I am afraid Opencpn will not be capable of what you intend to do, realtime radar? it should be built into the coding, like RNS,
MaxSea,
Garmin,
Furuno, etc. and then , only for equipment of the same brand.
Furuno radar-Furuno
software, etc.
For
autopilot control, instrument data, and plotting , you dont need SeatalkHS, an E85001 nmea-seatalk box would do.
If you still want to connect via SeatalkHS go back to 32bit RNS, it is prepared for that.
Good luck. alex