Herding cats.
If I'm understanding you correctly:
The recips will be in the complete control of the link list owners and, being that the recips are being delivered to the free site dynamically, the free site builder could not edit them to meet the rules of opposing link lists or even to simply pretty them up to match their free site's design.
Also, what happens when I guy like me gets up in the morning and decides to modify his recip to look like this:
<div style="
width:750px; height="400px; background-color:#000000; color:#ffffff;
font-size:78px; padding:30px 100px 30px 100px;">
<a href="http:xxxxxxxxxxxxx.com">MY LINK LIST</a>
</div>