Using C-channel for the back half?

[abadsvt]

I have decided to not build a complete frame from scratch and just modify the stock frame. I am going to rebuild the back half similiar to the pic i borrowed from FNLOW69. Hope he doesn't mind. I was wanting to build it out of 2x4 C-channel. The reason i want to use C-channel instead of tube steel is because i am going to be puting the gas tank behind the rear axel and would like to have all the fuel lines and brake lines protected inside the channel. They have 3/16 and 1/4" C-channel. I was thinking about using the 3/16 and then puting a large piece of 3/16 steel on the inside and outside for extra stength (gussets). What do you all think about this? The factory frame is made out o 1/8 C-channel so i don't see how this will be weak or bad. Please give me your opinion. Thanks

Here is a pic on how i am going to do the rear end.