I found the perfect solution for myself at the local DJ store in the form of a record bag. It opens at the top and it easily fit all my nav gear comfortably and has other pockets around the bag to store torches, fuel drains, maps, licence etc. Mine dosent have wheels but had a sholder strap and can also be used as a backpak. Try this web address for this bag i came across. if its not quite what you're after try ebay. Do a search for DJ bags, and there is a an online store that sells similar types. Now that you have brought the topic up i might order one with wheels!!! hope this helps you.
UDG Sling Trolley Bag - Black - Buy online or in our store at Spank Records Sydney, Australia ::