The battery powered one is sure to run down whrn you need ot the most. The AC powered one is the way to go unless it means stringing together 2 or 3 50 ft extensions.
For the airbox mods, you can just use a 1/2 inch drill and carefully make several holes through the filter and airbox bottom. When you replace the filter, just cut off the bottom of the old one to use for a drilling guide on the new one.
