Lift kit for 2021 R-Pod 196 HRD

That lift (structural tubing) is stronger than the original frame tubing.  It's stronger than the lift kit offered by forest river. You will not have any issue with that. If i were going to critique their work, I would have asked them to put a round stand off the same length as the inside dimension of the walls, to prevent the slight "sucking in " where the bolts go thru. If I may be so bold. 

I like what you did, but in researching the lift for our 195 I am going with a longer tube. It only makes sense that FR touting the Hood River Edition as an off road unit should put this on at the factory. The only complaint I have is exactly what you have overcome with the tank drains so low.

Yes, you need attachments to be out at the ends of the risers. Or probably easier and more secure would be to use some steel plate as webbing and Tek screws to attach one tube under the other, then attach the axle to the lower tube. I don't think that would cause any issues as long as there was access. Possibly the risers tube could be welded to the frame lbut someone with experience welding in proximity to wood would need to comment on the likelihood of damaging the floor.

It's not the vertical load, that doesn't change with the lift kit. it's the torsional moment that's the issue. The torsion axle twists the frame. By adding the lift kit you increase that if you hit a pothole which pushes the wheel back as well as up.

Look at the FEA modeling in this link:

Torsion axle model

One of the bad things about torsion axles. We've had at least one rpod frame fail at that high stress point.

By spreading out the attachment points you reduce the stress on the frame because you can create the same resisting moment with lower force on the attachment points (moment or torque equals force x distance).

Hope that makes sense.