I too only ever sit in the front seat when solo, this allows be to go out on the AMA's and balance the boat trying to keep the stupid AMA's out of the water. Like you I feel totally trapped just sitting in the back seat, and its hard to do the center board, and control all my extra sails and rigging from the back seat.
However I had for a while a heavy duty tramp/spray skirt system on the boat that did work out pretty well for hiking out from the back seat. Well I had it for a while but never used it, so it got recycled into new front spray skirts, when my old front spray skirts wore out. I mostly only used them in the winter when my daughter would come down from Chicago over the holiday season, she would go out sailing with me often, but always complained about getting splashed by the cold water when in the rear seat in the winter (we don't have that problem in the summer LOL), so I made them for her.
I kind of modeled the spray skirt system similar to what you see on the Windrider 17's. Both the front and rear spray skirts are super heavy duty and you can sit on them or stow gear on them. I'm kind of cheap so I ended up using just standard heavy duty screen material (the kind they sell for pets at Home Depot), I then got some of those 4 ft orange 3/8 dia fiberglass rods (home Depot, they are about $2-$3 bucks ea). The rear skirt is about 3 ft wide at the front, and hooks through the regular tramp straps (just loops of paracord looped thru the tramp straps, and around the 3/8 rod). The inside I secured the inner 3/8 rod to the rear AKA brace, tied to the rear handles, and had a piece of para cord running across the hull just behind the rear seat (tying the two rear skirts together). The connecting leg that formed a triangle shape when from the outer edge on the front, then tapered to a point where the rod holder are forming a triangle spray skirt. I ran a 1/4" nylon rope through some 3/8 PVS water pipe where I tied the back around my motor mount (the motor mount is just 1 1/4 PVC sitting in the rear rod holders), then at the front I tied a small loop of spectra string that wraps around the rear AKA bar, then slips over the tabs (the tabs that hold the AMA bungy's on). to break the boat down, you just unhook the tramps, and lift that loop off the bungy tab, then fold the skirt over the hull for transport.
The reason I use the screen material vs tramp material is the wind blows thru the screen material much more easily, and doesn't become a kite. However the screen material only blocks 90% of the water, some small spray still gets thru. I suppose in areas where you need to reduce splash more than normal you can put a double layer of pet screen in (it's outdoor screen, so no issues with sun and water exposure).
Once you have the outside structure it's pretty easy to add the screen material, you just cut it out 3 inches larger per side than needed, fold it over the 3/8 rods, then hot glue the seam. In the high stress areas (like the corners), I usually sew in some fishing line with a needle and thread before applying the hot glue.
Of course you have to have the super heavy duty spray skirt on the front of the boat also, the 1/4 nylon line for that goes from the bow to a clip that clips onto that stainless cleat in the center of the AMA. Once you have both front and rear spray skirts on, you no longer need the regular ama brace so I typically just leave that in it's parked position so it is out of the way. The front spray skirts work the same way, I just unclip one clip then fold the skirt over the hull for transport. It actually works nicely because the spray skirts hold all my other crap down while going down the highway, and don't get damaged by the wind (some of my older spray skirts got ripped to shreds whenever we did the 300 mile trip to Key West on the highway. I see no reason you couldn't climb about the boat over the rear spray skirts, though we never tried it, we do that all the time over the front spray skirts (which are the same basic construction, actually the current front ones used to be the rear spray skirts). I'll probably make another set of rear spray skirts before my daughter comes in January, I'll use the same design, as it works really well, and only takes a couple of hours to make them, plus they are very inexpensive (if I remember, everything was under $40 bucks).
Hope this helps.