Looks like a good start, I like the two inner curved tubes, (a little style). However, as you mentioned, you do need more mounting points. I'd say at least one on each side. I'm sure the two mounting plates are thick but with nothing behind them, a good smack will probably bend them backwards. Here's how I ran my lateral supports. I even allowed them to bolt up to the factory holes that mount the tow points. Keep up the good work.
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'86 4Runner 5" SAS
'97 4Runner
'05 Corolla
'00 F250 PowerStroke