Feasible floor frame idea?

I've been pondering a floor frame idea all evening and now it's time to ask for help.
Background: I just purchased a 4'x8' Harbor Freight trailer frame and plan to build a 5'x8' teardrop. Reading through past posts, I've found most people, when building a TD with 6" overhangs use 1"x2" framing for the floor (+ply/insulation) and weld 6" 'wings' on to support the side walls. I'm building a fairly lightweight TD using mostly 'leftovers' from the house restoration...it won't have any cabinets, just a couple of 1"x14" cypress shelves, a simple sealed/primed/painted exterior and interior, plexi windows, etc...
I had planned to use 2"x2" framing, 1/2" ply, and 3/4" insulation for the floor frame since I already have all those materials leftover from past projects. When I approached a friend about welding on the 6" 'wings' he laughed and said it was major overkill considering how light the TD will be and the way I plan to frame the floor. He said if I was really paranoid about the side walls flexing, I could change a couple of the 2"x2" crossbeams in my sketch to 2"x4" (which I also have) and there'd be no way the side walls would budge.
If he's right, all I'll have to buy for the floor are bolts (I really hope he's right, LOL!), but I wanted to ask the experts...
What do you think? Will this floor frame be solid and sturdy without the additional 6" welded extensions? Any input will be appreciated!
(sorry, the wheel placement/width isn't quite to scale)


Background: I just purchased a 4'x8' Harbor Freight trailer frame and plan to build a 5'x8' teardrop. Reading through past posts, I've found most people, when building a TD with 6" overhangs use 1"x2" framing for the floor (+ply/insulation) and weld 6" 'wings' on to support the side walls. I'm building a fairly lightweight TD using mostly 'leftovers' from the house restoration...it won't have any cabinets, just a couple of 1"x14" cypress shelves, a simple sealed/primed/painted exterior and interior, plexi windows, etc...
I had planned to use 2"x2" framing, 1/2" ply, and 3/4" insulation for the floor frame since I already have all those materials leftover from past projects. When I approached a friend about welding on the 6" 'wings' he laughed and said it was major overkill considering how light the TD will be and the way I plan to frame the floor. He said if I was really paranoid about the side walls flexing, I could change a couple of the 2"x2" crossbeams in my sketch to 2"x4" (which I also have) and there'd be no way the side walls would budge.
If he's right, all I'll have to buy for the floor are bolts (I really hope he's right, LOL!), but I wanted to ask the experts...
What do you think? Will this floor frame be solid and sturdy without the additional 6" welded extensions? Any input will be appreciated!

(sorry, the wheel placement/width isn't quite to scale)