How to use RDCMan with multiple monitors and scaling to be full screen when client display is larger than host display?

Question

My work computer has 2 1080p displays but at home setup is 2 4k displays - both running Windows 10. When I remote in, the scaling is off and it is slow.

Currently, I am using regular RDP with "Use all my monitors for the remote session" checked but there is about a 1-2 second lag for all my actions. Looking at my host computer's display, I see it is outputing 4k when I do this.

RDCMan is Remote Desktop Connection Manager 2.7.

One issue I have been having with RDCMan is when clicking on "Tools > Options" then open the "Client Area" tab, setting an "Client Area Size" does not change and keeps reverting to 2356x1200.

"Use multiple monitors when necessary" in Tools > Options > Full Screen Options apparently seems to only apply when the host is larger than the client (the opposite of my case).

Ideally, I think I would be RDCMan would connecting using 1080 for both monitors and streching them to fit on my 4k monitors on full screen. How can I use full screen on my home 4k display quickly to connect to my work 1080p display?