Buy the best moving map GPS you can afford. Learn how to establish the altitude of controlled airspace from it without having to pause for thought. Preferably wire it in to the aircraft power supply and in any event keep a spare set of batteries handy. Update the database as often as you need to (generally after any major airspace changes in the part of the world you fly in).
Fly around for the next 20 years and never be lost.
If the above plan should fail you, call D&D on 121.5 Don't try and rely on any other options at that stage. If you are lost, you are lost.
P.S. I'm in the bunker with IO540.