I am concatenated the entire "letter" into one formula field and I am using HTML tags in that as the way to format that one field for the entirety of the way I wanted the letter to 'display'. This way when the letter is exported as an rtf it is just one section with multiple paragraphs.
For values that are still needed to be added by a user I decided to use color and bold tags and an "insert specific value here" text to prompt the user to 'finish the exported letter' before printing it.
When you place that formula field in the report canvas set it to be displayed as text interpretation = HTML text
I would recommend a simple test before spending hours building a complex.
Like build the letter header and pull in a few data items and a few places to 'add content'.
Export that and try editing it.

I am creating a formula field in crystal.
In that formula field is where you concatenate the values

"<p>Dear " + table.FirstName + ",</p>" + "<p>The following foods <b>Add foods here</b> are needed for dinner.</p>"

I am not sure this idea will work for what you need but it was a work around I found that I was able to get value out of.

You can also make it so it creates multiple 'letters' at once for different 'customers' by grouping on a customer ID. If you need to roll multiple rows into one item you can do that via a shared variable and then make your ultimate output place on the group footer.

Right click on the formula field
select Format Field
select Paragraph Tab
Change "Text Interpretation:" to HTML text