How to handle Twitter Bootstrap fields with Thymeleaf Spring and less code

I need some advice how is a recommended way to handle Twitter Bootstrap fields with Thymeleaf. I know that recommendations are not so easy, so I wrote my thoughts about it and hope you can comment it. At the end there a some concrete questions. First I tried a fragment which shows what is needed to generate

<div th:fragment="textfield">
  <div class="control-group"
    th:classappend="${#fields.hasErrors('__${fId}__')}? 'error'">
    <label class="control-label" th:for="${fId}"
        th:text="#{model.__*{class.simpleName}__.__${fId}__}+':'">
       FirstName 
    </label>
    <div class="controls">
        <input type="text" th:class="${inputclass}" th:field="*{__${fId}__}" th:disabled="${disabled}"/>
        <span class="help-inline" th:if="${#fields.hasErrors('__${fId}__')}"
            th:errors="*{__${fId}__}"></span>
    </div>
  </div>
</div>

which can be used with

<div class="control-group  replace" th:include="templates::textfield" th:with="fId='userId'" th:remove="tag">
        <label class="control-label replace">Benutzer-Id</label>
        <div class="controls replace">
            <input  type="text" value=""/>
        </div>
</div>

or in short

<div class="control-group  replace" th:include="templates::textfield" th:with="fId='userId'" th:remove="tag"/>

It's not very flexible about the input, so you need for a checkbox an own fragment.

Next I choose the layout-approach:

<div layout:fragment="bsfield">
  <div class="control-group" th:classappend="${#fields.hasErrors('__${fId}__')}? 'error'">
    <label class="control-label" th:for="${fId}"
        th:text="#{model.__*{class.simpleName}__.__${fId}__}+':'">
    FirstName </label>
    <div class="controls">
        <span layout:fragment="bsinput" th:remove="tag">
        <input type="text" class="replace" th:field="*{__${fId}__}" th:disabled="${disabled}"/>
        </span>
        <span class="help-inline" th:if="${#fields.hasErrors('__${fId}__')}"
            th:errors="*{__${fId}__}"></span>
    </div>
  </div>
</div>

Which is very flexible because I can define my input directly.

I can use it shortly with

<div layout:include="templates::bsfield" th:with="fId='firstName'" th:remove="tag">
  <div layout:fragment="bsinput">
    <input type="text"  th:field="*{__${fId}__}"  th:disabled="${disabled}"/>
  </div>
</div>

or more prototype style

<div class="control-group" layout:include="templates::bsfield" th:with="fId='lastName'" th:remove="tag">
    <label class="control-label" th:remove="all">Last Name</label>
    <div class="controls" th:remove="tag">
        <div layout:fragment="bsinput">
        <input type="text" th:field="*{__${fId}__}"  th:disabled="${disabled}"/>
        </div>
    </div>
</div>

Both variants has still a lot of boilerplate. So I think about the following solution inspired by Playframework helper.

<input type="text"  th:bsfield="firstName"  th:disabled="${disabled}"/>

and writing a Processor which creates

<div class="control-group"
    th:classappend="${#fields.hasErrors('${fId}')}? 'error'">
    <label class="control-label" th:for="${fId}"
        th:text="#{model.__*{class.simpleName}__.${fId}}+':'">
    FirstName </label>
    <div class="controls">
        <input type="text" th:class="${inputclass}" th:field="*{${fId}}" th:disabled="${disabled}"/>
        <span class="help-inline" th:if="${#fields.hasErrors('${fId}')}"
            th:errors="*{${fId}}"></span>
    </div>
</div>

and replace ${fId} with the value of bsfield in this example "firstname". After that Thymeleaf should recompute it (setRecomputeProcessorsImmediately (true);) For the prototype I think it's necessary to write a JS-Solution.

I'm unsure if this is really clever or a misuse of Processors. Furthermore I'm unsure how much time a beginner need to write such a processor. Are 4 hours realistic or more a few days?

Would appreciate if someone can give me a hint.