Adding prebend is done by sweeping the spreaders aft and cranking on diamond tension. Older soft rigs did not have much spreader rake adjustment if any. Adding prebend to a TheMightyHobie18 will mean you'll need a custom cut mainsail and there not be class legal any more.

Placement of the diamond attachment points is not that relevant to generating prebend. There have been many iterations of the attachment points. Currently, have a single turnbuckle on the front of the mast is in fashion...makes it easier to quickly adjust tension on both cables at the same time. The carbon T mast runs the lower diamonds into the mast with the adjuster mounted in the mast base...a large single adjustment nut sticks out the bottom of the base.