5th wheel/frame rails

Probably not going to be low enough. I'd consider something more like this myself:
Cozad! Trailers - Custom Truck Ramps

 

Pee Dee Trailer......Florence SC. Its about 1/4 mile from the Petro.

 

You have to call them ahead of time so they can get the steel in. They don't weld to the frame, bolt only.

 

Remember to measure the height of the pickup rollers on the trailer you have access to dropped on level ground and consider having the ramps built to pick up 2 inches lower in case of uneven ground.
I had mine built to be able to pick up trailers at 36 inches and never had any trouble even with extended neck 55t low-boys and more.
The ramps you pictured may work for most 25t or 30t trailers but by the time you are looking at 40t or more you may have trouble getting under them.

 

Yes call them. Make an appointment. They'll build you the best ramps and install them......Theyll build exactly what you need!