Disc mowers - cutting height?

It seems that a lot of disc mower manufacturers boast about how close to the ground they can cut. I understand this is desirable for some crops like alfalfa. But we are planning to grow some tropical forage crops that do better when cut higher up, at around 25 centimetres (~ 10 inches) above the ground.

 

I see that New Holland has a mower http://ift.tt/21PKPvGthat has an option for extra-high skids (BioMass option) with height range up to 7-3/4 inches. They say "Lift lock out channels stop the cylinders mid-stroke to maintain good flotation, even when cutting well off the ground."

 

I'd like to ask:

 

1. Is it necessary that disc mowers are in contact with the ground when mowing... do they have to skid along on their shoes?

 

2. If the answer is yes, then do you think it would be relatively easy to add some "spacers" or "extra metalwork" of some sort to increase the height between the cutterbar and the shoes to raise the cutting height?

 

3. Is there some reason why customising the mower to raise the cutting height might not work, for example due to changes in the geometry that might affect alignment of the drive shaft, etc?  

 

Thanks. 

 

 

Disc mowers - cutting height?