asp.net core WebAPI get subset of Generic Request Object

Question

I am new into asp.net core webAPI. I have created a Controller method that taken a request object.

    [HttpPost]
    [Route("/api/DoWork")]
    [ValidateModelState]
    public virtual IActionResult DoWork(CustomRequest request)
    {
          //TODO: implement this method 
    }

Now this CustomRequest calss is generic class, which have multiple properties and depending upon the client/tenant will populate/set values for some of the properties.

Example : Suppose CustomRequest class structure is,

public partial class CustomRequest
{ 
    public string ReqId { get; set; }

    public DateTime? BusinessDate { get; set; }

    public DateTime? CurrentDate{ get; set; }
}

So Customer A can only set values (or send values in request) ReqId and BusinessDate and Customer B send values ReqId and CurrentDate. As to proceed with business operation either of the date is required.

It's also previously decided which client will send which of the values, and this number of properties is large.

So I was thinking of creating a relatively small class which will be subset of CustomRequest class and sufficient enough to process business operations. And I can think of two options to proceed with that.

1. Write code inside my controller action to create small sub set class and then call another method that expect only the subset class
2. Use Custom Model binders to create that small subset class and change the method signature.

My question is: What is the best way to handle this situation option 1 or 2 or any other option? Best way in terms of performance and customization option available (like in option 1, i don't think we can use ModelState)

Any help or guidance...