Globally modify left part URL in MVC 4 / 5 - asp.net-mvc

Question

I am using IIS 8.5 with MVC4 and MVC5.
Let´s assume that I have two websites where the URL of the first (WS1) is:
http://myapp.example.com
and the second website (WS2) URL is:
http://myapp.example.com/sub
(and is located on another port to which I want to forward)
Now, my problem is that all URLs generated by MVC (links etc) will use the left part of the URL and remove /sub within that application. Let´s say for instance that in WS2 I want to redirect the user to http://myapp.example.com/sub/login but it will become http://myapp.example.com/login instead.
I have tried IIS URL rewrites but it will only work first-time request that actually contain the /sub part, the URLs generated by MVC of course remains erroneously without the /sub part.
<rewrite>
<rules>
<rule name="Rewrite">
<match url="^Sub/(.*)" />
<action type="Rewrite" url="http://myapp.example.com/{R:1}" />
</rule>
</rules>
<outboundRules>
<rule name="Response Status Update" preCondition="ResponseStatus" stopProcessing="true">
<match serverVariable="RESPONSE_Location" pattern="^/(.*)" />
<action type="Rewrite" value="/Sub/{R:1}" />
</rule>
<rule name="RewriteRelativePaths" preCondition="IsHTML">
<match filterByTags="A, Area, Base, Form, Frame, Head, IFrame, Img, Input, Link, Script" pattern="^/(.*)" negate="false" />
<conditions>
<add input="{URL}" pattern="^/Sub/.*" />
</conditions>
<action type="Rewrite" value="/Sub/{R:1}" />
</rule>
<preConditions>
<preCondition name="IsHTML">
<add input="{RESPONSE_CONTENT_TYPE}" pattern="^text/html" />
</preCondition>
<preCondition name="ResponseStatus">
<add input="{RESPONSE_STATUS}" pattern="3[0-9][0-9]" />
</preCondition>
</preConditions>
</outboundRules>
</rewrite>
My question is how I can accomplish this. Using another subdomain is not an option.