[asp.net-mvc-3] How to set a hidden value in Razor

I know that what I'm trying to do is bad idea, but I have specific constrains for now.

I have multiple sites, using one and the same MVC3 code base. For one of them the requirement is to hide some required fields from the form.

I know that the best approach is to modify the controller to set the defaults for these fields, but I'd like to achieve this modifying only the view for this particular site w/o changing the code.

So, how do I set a particular model property to a default value in the view? The ideal should be something like:

@Html.HiddenFor(model => model.RequiredProperty)
@model.RequiredProperty = "default"

EDIT: more explanation

So, actually this is in a sub-view, which is used by 2 different main views. I need these properties set only if one particular main view is used, and not the others.

So, I guess the setting to default need to go to that particular "main" view. Looks like I can not use HiddenFor in the sub-view, and then Html.Hidden in the main.

Is there a way to check in the sub-view which is the outer view?

While I would have gone with Piotr's answer (because it's all in one line), I was surprised that your sample is closer to your solution than you think. From what you have, you simply assign the model value before you use the Html helper method.

@{Model.RequiredProperty = "default";}
@Html.HiddenFor(model => model.RequiredProperty)

If I understand correct you will have something like this:

<input value="default" id="sth" name="sth" type="hidden">

And to get it you have to write:

@Html.HiddenFor(m => m.sth, new { Value = "default" })

for Strongly-typed view.

How about like this

public static MvcHtmlString HiddenFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, object value, object htmlAttributes)
    {
        return HiddenFor(htmlHelper, expression, value, HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
    }

    public static MvcHtmlString HiddenFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, object value, IDictionary<string, object> htmlAttributes)
    {
        return htmlHelper.Hidden(ExpressionHelper.GetExpressionText(expression), value, htmlAttributes);
    }

Use it like this

 @Html.HiddenFor(customerId => reviewModel.CustomerId, Site.LoggedInCustomerId, null)