Workarounds for non-4K AV receiver with 4K TV

Here's the situation:

I'm looking to buy a 4K TV, but my current AV receiver isn't fully 4K/HDR compliant and I can't afford a new receiver as well.

I have two 4K playback devices (PS4 and Xbox1).

Receiver has 4x HDMI inputs and 1x optical input.

I figure I have two options:

1. Plug both PS4 and Xbox One into the TV via HDMI, then use ARC or optical cable to send audio to receiver.

2. Attach HDMI splitters to the outputs of the PS4 and Xbox One, then connect them to both the TV and the receiver via HDMI.

The problem with 1 is that I'm not sure if it will pass through higher than 2 channel audio, but it definitely won't pass through Dolby-HD or DTS-MA etc.

And the problem with 2 is that I'm not even sure if it will work - will the receiver still process the audio from the HDMI when it is accompanied by incompatible video?

Any thoughts on the two options would be appreciated, or any other ideas?

Thanks

EDIT: And will an HDMI splitter allow CEC?