is it blowing up form not staying stable, add a few delta winglets to the "lifter stages" and is thats not enough Dv, go outwords on teh redial seperators, also move your fuel linbes done to teh bottom and make sure they are A all there, and B in teh right drection, if the fuel burns not all "even" it will become unstable as you go up, if its blowing up on teh launch pad, add the launch stablizers, and set them to detach as you fire your engines. second you Can use the nukes to "help carry" the whole rockent up of you use the set up form teh last pic you posted, just fuel line into it, untill all your outter stages are gone it wont touch the inner fuel tanks