Good to see you on the forum. Hopefully, we will see you a lot more in the future.
You sound like someone in need of a TGV from Sunfire.
You might also look to a Dtrovision HDMI switcher for your short-term video swithing needs. I find them to be the best and pretty affordable. Not sure how you can switch the 5.1 audio in the analog domanin if you need two sets of 5.1 ins. I bet Niles or someone like that makes what you need.
In the end - I would just sell the TGIII and buy a TGV.
Jerry Del Colliano