A little bit of theory on fragments.
When you design a form with fragments, the main XDP contains references to the fragments (which are also XDPs). Those references are resolves by LiveCycle Forms (fragment XDPs are imported into parent XDP) before the PDF is generated. So we really pass an XDP with no fragments to LC Forms, therefore the PDF doesn't have a concept of fragments.
Now back to your question. If you design you XDPs with fragments and do a PDF Preview, before the PDF is rendered, the fragment will be resolved and the resulted PDF will not contain any fragments. You can save that PDF back to the file system and reopen it in Form Designer and save it as an XDP. This way you'll end up with an XDP that looks exactly the same but with no fragments (all the fragments were resolved by the creation of the PDF).
Then save that new XDP and you should be able to pass that XDP to LiveCycle Forms 7.x since it doesn't contain fragments.
On a different topic, if you use the turn key install of LiveCycle ES, you can get it up an running pretty quickly (hours). You can get a trial version and play with it. Maybe you can do that while you get you complete environment up and running.
Let me know if that works.
Jasmin