I am normally loath to suggest something that is counter to what an OP is asking about, but...well, sorry

If you're track riding, wear whatever the most comfortable, safest suit is. When you come in from your session, it's 30+ minutes before you have to ride again...just take the suit off. If you wear some Under Armor style stuff under it, it comes off and goes on easy.
That said, if you need a new suit, and don't mind waiting 12 years or so for Vanson to get around to making you one (no I'm not bitter) that dual zipper design does make getting them on and off easier.
Cheap-and-easy tip: find a bungee cord that is tight enough around your leathers that you can use it as a belt. Get off the bike at the end of your session, put the cord around your waist, then get the top half of the leathers off and let them hang...the bungee will mostly keep the bottom part in place.