Another option is to split the difference on chainline and run with two chainrings. You can establish a pretty wide gear ratio difference with the same (or similar chainlength). Just finished setting this up on a MTB with 32x18 and 36x13. Got me a wikked split for trail riding and riding to the trail, just planned to have the best chainline in the most critical situation (inside ring, more likely to catch and derail than the outside).
+3mm and -2mm is not too bad.

Just an idea if you're looking for a wider range. You may find that, depending on chainstay length and gear choice you may not have much range of motion left in the eno otherwise.