You do NOT need a nice Cannondale road bike to do trails. A fast bike will just let you drop your wife and get you in trouble. All you need is a hybrid or mountain bike. Which you have. More expensive models will be lighter and shift better, but that's about it. If you want to upgrade something, first get your wife - not you - some slightly skinnier slick tires that will roll better and let her keep up with you more easily.
The cost of a lightly-used, low-end recumbent wouldn't necessarily make your eyes water, and most can be transported on a hitch rack. You probably wouldn't end up with a matched set, but they're like weights - a lot of people buy them with good intentions and then don't use them; and you can snarf them up for cheap.
Last edited by BlazingPedals; 04-20-15 at 06:51 PM.