Ok, I do alot of riding behind a sea-doo PWC, so I know where your coming from (hopefully will be getting a shiny new boat next summer!) I know alot of people will tell you to just 'give up' boarding or buy a roam or a wakeskate but there are some tricks you can do behind a Doo.
To accomplish good wake jumps, get comfortable riding up to speed, when you feel good try to keep your speed as consistent as you can- somewhere around 21 mph (i know its tough you have to have a somewhat decent driver). At this speed, the wake of the Doo is the cleanest it'll get and isn't like 200 feet wide; its pretty narrow. I suggest shortening your rope to 55 ft or 60 ft if you can take links out of your line, depending on how bad the spray is from the jet. Keep practicing your wake jumps and you will eventually to be able to go completely W2W ((wake to wake) completely jumping across the center of the wake). You won't be getting 10 feet of air, considering you only have a foot-high wake to jump off of, but if you suck up your knees into your chest in the air you'll be able to get maybe, maybe, 3.5 feet with practice.
Also, you can do many surface tricks, which are tricks where your board does not leave the surface of the water. Try slowing down the speed of the PWC a bit for the first couple of tries to prevent faceplanting, and if you'd like you can take off your fins. To do a surface 180, when riding regular just twist your body and whip the board around so your riding switch. Then let go with your trailing hand and get alittle used to riding switch. Once you've mastered the surface 180 you can try a surface 360 by passing the handle behind your back.
Some other tricks that are possible behind a Doo are ollies ((jumping off the water in the flats)flats- the areas outside the wake), ollie 180's, 180's (rotating in the air after jumping off the wake), and butterslides which are like 'boardsliding the wake'.
A wakeskate (basically a skateboard made to ride on the water, no bindings) isn't that bad of an idea even though i shut down that idea at the beginning of this post. I got one this year and it's a blast to ride, especially behing a PWC.
Hope some of this helps & Good Luck!
P.S.- Do a search on the forum for 'progeressive edge', 'wake jumps', or anything else you have a question about. Chances are someone asked about it before you, and these threads give you instant answers!