Extended T1.x rules may be okay for us, and it seems easy to check in MWS, you can click on Tools and then "Check Deck Legality" and then click the Extended T1.x button
The rough gist of this (ignoring the sideboard limit) is :
Legal Extended Editions: "9E", "SOK", "BOK", "CHK", "FD", "DS", "8E", "MR", "SC", "LE", "ON", "JU", "TO", "OD", "AP", "7E", "PS", "IN", "PY", "NE", "MM", "UD", "6E", "UL", "US", "EX", "SH", "TE"
How does this sound for people ? should be easy to check deck legality and look at the short name when selecting a booster deck to make sure it's a legal one.