You should be able to have enopugh access for one of the two most common types of wrenches: End-cap & strap.
If you see examples of each of these designs, as well as your application, you should be able to figure out which one will work best for you. Try:
http://www.lislecorp.com/tool_browse_list.cfm?browse=9
The screwdriver trick can work ... but it should only be used once the canister is deformed. Often the screwdriver will tear through a filter and remove chunks of it but the baseplate remains stuck against the gasket-mating surface. Then, you need to take pliers such as vicegrips to try and get the jagged baseplate to spin off.
Best to use the proper tool, instead. And when installing the filter, as tight as you can get it by hand should suffice.