It's a great start! I assume you probably have some plans for a belly pan for electronics and the like, but you should make sure it's at least somewhat structural. The flanges on the front and back rails are good, but they
won't hold up to abuse * without some stiffener in the form of a structural belly pan, or additional center supports. Bumpers will help some, but you don't want to rely on those.
*These pictures are of the damage to the reinforced repair of a 2x2x0.125" aluminum angle, since the original 1/8" sheet chassis couldn't hold up.