Been there done that...
The 'Sandpiper' (mini size) yachts had a jib on a couple of them, the positives were it gave a bit more grunt in light winds but bad news in stronger winds it made turning virtually impossible due to the light down pressure on the front wheel which made the yacht lethal in tight sailing sites like car parks.
Jibs also lower the top speed as when speed increases all they do is flap causing significant amounts of drag.
If you were to use one it would need to be self tacking (most water yachts aren't) you might also think of putting roller furling on it for safety on the beach.
On BIG yachts like used in the National Geographic documentary "Wind Raiders Of The Sahara" used them well as they needed the extra power and keep the centre of effort low as possible to deal with the sand hills they encountered.
The original trip across the Sahara was in the mid 60's the doco was a reenactment that was done in the early 70's.
(Here is a cover of the original trip when it was printed)

Was a good thought tho.....

The Sabre 'bum' actually sits very low to the ground and you don't need any more down force. The original Sabre axles were cast alloy with v webs in the casting... they bent, the next model came with fibre glass axles which worked great.

If you were to ever build an "expedition" specific yacht (eg. from a trip from Kingstone to the mouth of the Murray) a jib would be certainly be there for consideration as well as 300mm ground clearance, baloon tyres and hand steering.

Hi Beachballs,

Do you have a picture of your Sabre? Their sails varied quite a bit from memory & some may be more suited to a jib than others.