SFBD question

dude you have to figure how close your rear bags and your front bags are goin to be apart. the less distance between the front an rear bags the shorter the frame will be in length... and the stronger it will be. the weight of the truck doesnt sit on the front and rear of the frame... it sits on the bags... for a mini truck i cant see the under the cab of the frame being more than 4 or 5 ft long... so get a piece of 2x2 1/4 wall and cut it 5 ft long and see if it bends... i think youll be ok..