problems with cross field custom validation in go

I'm trying to learn golang custom validation but running into a lot of trouble. Here's the code for what I've been attempting:

package main
import (
        "reflect"
        "github.com/go-playground/validator/v10"
        "fmt"
)
type TeamMember struct {
        Country string
        Age int
        DropShip bool `validate:"is_eligible"`
}
func CustomValidation(fl validator.FieldLevel) bool {
  /*
    if(DropShip == true) {
       httpresponse = curl https://3rd-party-api.com/?country=<Country>&age=<Age>
       return httpresponse.code == 200
    }
    return false
  */

  b := fl.Parent()
  fmt.Println(reflect.TypeOf(b))
  fmt.Println(reflect.ValueOf(b))
  c := reflect.ValueOf(b).Interface()
  fmt.Println(c.(TeamMember))
  fmt.Println("============")
  return true
}


func main() {
  var validate *validator.Validate
  validate = validator.New(validator.WithRequiredStructEnabled())
  _ = validate.RegisterValidation("is_eligible", CustomValidation)
  teammember := TeamMember{"Canada", 34, true}

  validate.Struct(teammember)
}

You can see the validation logic that I'm attempting in the code comments...If the DropShip field is true, then I need to submit the Country and Age to another API to see if this team member is eligible.

The problem is that I'm struggling with the reflect library to access the Country and Age fields in the TeamMember struct. The fmt.Println(c.(TeamMember)) line crashes my program.

Can someone give me an example of how to access the other TeamMember fields? Or is my approach to validation in violation of the idiomatic way of validating in golang?