I've never managed to really hurt the wings on a BiSlob. I went a few steps past the flying models plans. Instead of the 1/2" square leading edges, I've always used 3/8" square. Also I only used 1/32" for the sheeting on the surfaces that mate to the fuselage. My fuselages usually blow up, and I've torn both wings off many times, but the wings and tail surfaces never really take the heat. On my most recent Slob, I decided against the formers cut from 1/8" balsa sheet, and instead used 1/8 x 3/8" strips to build up the formers, think Sig Mustang. Since I'd had serious issues with fuselage damage, I added 1/8 x 1/4" diagonal stiffeners between the formers. So far the current Slob has been through many tail first landings, and hard touch n goes, and one catastrophic impact with the ground, no serious damage to the fuselage. The next one will probably have a gear on the top to match the bottom, and a reinforced vertical stab/rudder since it always gets knocked off.
The top half of the pic shows what it looked like after a full throttle, cartwheeling, completely uncontrolled crash. Both wings tore off, the wing struts were in multiple pieces, the fuselage between the wings were shredded, etc. The bottom half shows what it looked like 20 minutes later after putting the jigsaw puzzle back together. They're pretty hard to kill.