I don't really have an answer to your direct question.
I do, however, have a suggestion.
Put two sections on your form - and have a helper field in your data source (not on your form) that is a true / false field, defaulted to false. Hide one section when the helper field is true, hide the other when it is false.
When you submit via email, toggle the value of the helper field to true, then submit, then set the field to false. This way you'll have one section that is sent in your email, the other that is used when the form is filled out.
Put all your controls that are causing you issues into the section that is displayed when the users fill out the form. Use simple expression boxes (calculated values in IP 2010) or text boxes in the other section (bound to the same fields that the controls in the "fill out" section are bound to, of course).
This way you have a simple view that will more likely render correctly in plain text. Does that make sense?