I have a AFS 5500 BB:7 single screen that I am installing. I am realizing that I will run out of serial ports. The screen has the Red Box remote AHRS. Current hardware I have:

1) VPX Sport
2) TruTrak AP
3) Tt22 transponder
4) ARINC adaptor

I would like to install the following:
1) GTR200B
2) Val 2KR

I am assuming that if I use the SV network and purchase the SV Transponder and the SV ARINC, which would still leave me over the number of ports I need. I am thinking I need to buy another screen for the serial ports. I guess I could put a remote head on the transponder, but given I need to use the serial ports for the VPX and the AP, I am not sure the best way to go. Any recommendations?