NUnit TestFixture and TestCase

I have to write some integration tests with NUnit that should test HTTP endpoints. This means that URL should be shared across all test methods.

[TestFixture("http://my.endpoint.com")]
public class TestSuiteOne
{
   [TestCase(10, 20, Expected = 30)]
   [TestCase(20, 30, Expected = 50)]
   public int TestA(int a, int b, HttpResponseMessage sut)
   {
        // AAA.
   }

   [TestCase("XXX", "YYY", Expected = "ABC")]
   public int TestA(string a, string b, HttpResponseMessage sut)
   {
        // AAA.
   }
}

To get SUT value on each test run that comes from test suite attribute I know two options:

Option A (read SUT from class property)

public abstract class TestSuiteBase
{
    protected(string endpoint)
    {
        Sut = endpoint;
    }

    protected HttpResponseMessage Sut { get; }
}

[TestFixture("http://my.endpoint.com")]
public class TestSuiteOne : TestSuiteBase
{
   public TestSuiteOne(string endpoint) : base(endpoint)
   {
   }

   [TestCase(10, 20, Expected = 30)]
   [TestCase(20, 30, Expected = 50)]
   public int TestA(int a, int b)
   {
        // act (read content/response code/headers/etc); Making a call I do not consider as act.
        var actual = Sut.DoSomething();

        // assert
   }

   [TestCase("XXX", "YYY", Expected = "ABC")]
   public int TestA(string a, string b)
   {
        // act (read content/response code/headers/etc); Making a call I do not consider as act.
        var actual = Sut.DoSomething();

        // assert
   }
}

Option B (intercept test method call)

public class MyTestCase: TestCaseAttribute
{
    public MyTestCase(params object[] args) : base(Resize(args))
    {
    }

    // I do resize before method call because VS Test Adapters discover tests to show a list in the test explorer
    private static object[] Resize(params object[] args)
    {
        Array.Resize(ref args, args.Length + 1);
        args[args.Length - 1] = "{response}";

        return args;
    }
}

public abstract class TestSuiteBase
{
   [SetUp]
   public void OnBeforeTestRun()
   {
       var ctx = TestContext.CurrentContext;

       var args = ctx.Test.Arguments;

       // Making a call I do not consider as act.
       args[args.Length - 1] = MakeCallAndGetHttpResponseMessage(args);
   }
}

[TestFixture("http://my.endpoint.com")]
public class TestSuiteOne : TestSuiteBase
{
   [MyTestCase(10, 20, Expected = 30)]
   [MyTestCase(20, 30, Expected = 50)]
   public int TestA(int a, int b, HttpResponseMessage sut)
   {
        // act (read content/response code/headers/etc); Making a call I do not consider as act.
        var actual = sut.DoSomething();

        // assert
   }

   [MyTestCase("XXX", "YYY", Expected = "ABC")]
   public int TestA(string a, string b, HttpResponseMessage sut)
   {
        // AAA.
   }
}

Is there any more convenient way how to combine value that comes from TestFixture with TestCase?