topdek,

The old standby, the Vega box, is about as compact as there is. You may have to cut into the frame side rail to "sink" it in (or out depending on how you look at it). Just make sure you box in the relief cut with metal of comparable thickness to that cut out. There's a lot of leverage at work around the steering box. Some gussets may also be needed depending on how deep you have to relieve.