Tacoma beds have had issues cracking in the past. I have yet to see third gens with the issue, but seeing how our bed are basically second gen beds, I'm sure it's coming.
As a precaution I've added bed stiffeners from @ragofabrications. I'm hoping that's enough to prevent bed failure and am keeping an eye on the bed.
I have seen bed racks that mount into the floor of the bed (Jillian Rebekah's setup comes to mind). Most are on the rails though. I've considered having a buddy build a lightweight cage inside my shell that would allow the RTT to basically clamp through the shell. Might be a bit overkill though. lol