RGN Dillema.....

The riser is the pivot point the 5th wheel pins to.
A low rise is I believe 4 inches above the frame and a high rise as pictured is 10 inches, yours look to be 6 inch in the picture.
Then there are drivers who put spacers between the 5th wheel slider (or mount) and the frame. Tanker haulers sometimes do this to shift weight to the rear on smooth bore tanks.

 

4” of clearance on the lowest setting is plenty. I personally would leave the fifth wheel alone unless your rear deck is running down hill majorly. That could effect weight distribution on the rear axles. Ideally you want the rear deck level when loaded.

 

That looks good from here.

 

are there any drawbacks to a mini deck? no outriggers i guess

 

That conspicuity tape would be a deal breaker for me.