I have a poppy cover for my sportster and am very happy with it. Because of the design of my boat I am able to install the cover and tighten the ratchet while sitting on top of the cover and the back sun pad. Your boat is obviously bigger and something like that may not be possible.
The design of the drawstring pull is very similar to the drawstring pull on a pair of sweatpants for instance. The strings come out of holes placed in the sewed casing of the waistband. If you want the strings to come out elsewhere you could just make a hole somewhere else.
This principle should work with the poppy cover. The straps come out holes placed on the port side, but if you want them to come out somewhere else simply cut new holes where you want the straps to exit to the ratchet mechanism. The strap on my boat is floating (I believe) and is not anchored or sewed to the cover so it would just be a simple task of reorienting the strap to a new position in the cover. Since your cover is bigger there may be different issues, but I imagine it could be modified without much trouble even if there is a little sewing involved.