First of all, be careful that you aren't violating the LP ToS by hosting other people's sites under your account (unless you're doing a reseller account, or maybe a dedicated server). Assuming they are paying LP for their site hosting (keeping LP happy) and you just write their site frameworks for them...
It depends on how much stuff you want them to be able to edit, and how capable they are with the tools provided. If it's a simple block of text content, you could allow them to edit it as a separate file, and then use SHTML (instead of HTML) to allow embedding of this file. More complex things could be done by changing to PHP. However, it's up to them to use LP's file manager editor properly, and produce properly laid out and formatted HTML. If they can't be trusted to do this, you'll have to look for some kind of editor that puts them in a straitjacket. That, or something closer to a CMS that only allows them to do certain operations at a certain point, in a WYSIWYG manner.
I had the situation earlier this year with an elderly client (not at LP) who could just not grok the concepts of HTML tags, and insisted that he
had to use the cPanel WYSIWYG HTML editor to maintain the content. Even though I had pulled out the changeable text sections into simple little files, he still managed to screw it up every time (e.g., adding a new list entry as a paragraph
after the <ul>, rather than as a <li>
within the list). Eventually he gave up on the project.
