Several things influence rotation speed, and thus take-off distance. The fuselage station of the axle centerline is very important. You should hold this within 1/2".( see Chapter 9 and the back cover of Section I). Toe-in of your mains also has a powerful influence on rotation speed (not to mention tire wear!) Accept nothing less than a total of 1/4 of a degree to 1/2 a degree. (N26MS has 1/4 decree toe-in, and still has the original tires, with over 700 landings, 320 hours in one year).
If your tires are showing excessive wear, do not accept it, remove the axles and shim them until the toe-in is correct. This can be done guite easily by laying up one or two plies of BID on the strut and bolting the axles back on, gently tightening the bolts until the correct toe-in is achieved (by crushing the BID layup into a taper). allow the layup to cure, then torque the axle bolts to their proper value of 75 inch/lbs. ft/lbs). You could also use a commercially available taper shim.
Aircraft Spruce sells them in various taper values. Tire pressure can also influence take-off roll distance rotation speed (as well as tire wear), check your tire pressures regularly. Ground attitude of the airplane can also cause long take-off rolls. Your Long-EZ or VariEze should sit level to slightly nose up on level ground, when loaded to gross weight. If your airplane has a pronounced nose down ground attitude under the above conditions, it should be corrected. Note that a nose-down attitude during construction is normal, before the weight of the engine and wings are added.