You mentioned you can host a logic standard in a data center. I'm struggling to find any documentation as to how to set this up. I have a home server and would like to practice using some of the features found in standard, without incurring too much cost.
You might want to look at using Logic App Consumption - the costs are much lower to low volume / demo scenarios. For Logic App Standard, I think what you are looking for is just to run the standard edition inside Visual Studio Code. It's not very hard to set up, and it's getting easier. I have a video on it here www.stephenwthomas.com/azure-integration-thoughts/getting-started-with-logic-apps-standard/ It's almost a year old so I think things are more manageable now. Getting set up on a stand-alone server is more complex. I think you'd need ARC and a larger setup than you would want to deal with.
It's kind of an art vs a science. I would think the 2 core option would work perfect for that type of setup. It is more about the message volume & size and if you will have spikes in that load. At the end of the day, the only way to know for sure is to setup a dev environment and run some basic load tests. Once you get the sizing down, make sure you look at getting a reserved instance for 1 or 3 years. It'll save you around 30%. Also, if I read it right as of now Microsoft doesn't charge any fees if you do cancel early. Hope this helps.