All I can say is WOW, that is a very nice piece of work, and should get the job done. The only minor issue I'm seeing is there will be a bit of friction when rotating the mast, which is not a show stopper.
Here is a pic of my mast topper:
See the little rod sticking out the bottom, this is the pin point bearing, it spins on top of that cross bolt (the one that has the strap over it holding the sail up). It is pointed like watch bearings to reduce the amount of friction (just like the one on the bottom of the mast). Though it's not a huge deal breaker (it will work without the bearing) as the downward force goes up (example,,, pulling that Hobie jib tighter so it can work), the force required to rotate the main mast goes up. All this means is you will have to scooch and slide up to the mast and help it unfurl a little near the end (the last few turns). Furling the main in is never a problem an long as you furl it without load on it (pointing into the wind (which you should always do anyway)).
Best thing to do is try it, and if it is too hard to unfurl, just adding a pin point bearing should be pretty easy.
If you make an uphaul line (halyard) with a pulley at the top for the jib, I think you will be fine. On my halyard line I run the line through a piece of 3/8 PVC waterpipe so it can't get tangled in the mainsail when furling/unfurling). I then added an additional harken cleat on the far left position (hobies has the holes for the harken cleat all threaded and ready to mount, just be careful the screws are not to long so the screws don't interfere with the left AKA bar mechanism.
Hobie makes two different types of jibs for it's H16's One that is furlable, and the other which is not. Hopefully one of the H16 experts can look at your pic above and let us know which style this jib is.
You will likely need a rear stay line to help the jib keep it's shape, as the Hobies mast is very flexible, you need something to prevent it from bending forward. Side to side bending is not a problem (actually that bending action is important and you don't want to interfere with the side to side, or the backward bending of the mast). I used a 3/16 dia nylon rope (must be stretchy). When at rest there is almost no tension on the rear stay line, and when your sailing and the main mast gets bent back (which is normal) the rear stay actually becomes loose. The rear stay prevents the mast topper from turning sideways, and most importantly when on a downwind in a batwing configuration (main to the left and jib to the right sides), this rear stay takes some of the stress off of that little 1/4" bolt that holds the bottom of the mast holder to the hull (this 1/4" stud is the weakest link in the chain and must be protected (by the rear stay line)). I also run the rear stay line inside 3/8 PVC waterpipe, this prevents the line from tangling on the mainsail, and also keeps the ropes from getting all tangled, When done sailing I just break down the 3/8 pipe in the middle, fold it in half and lay it on top of the boat for storage. I have clips at the top and bottom that just snap to the back of the mast topper, then to the rear lifting cleat in the back of the boat.
Don't worry too much about side to side force on the mast holder, the design they have is very strong, and I have never had any difficulties with the strength of the mast itself (it is really strong, of course within reason)
To raise the mast I typically clip the rear stay to the back of the mast topper, I typically have the jib halyard (both ends) down near the bottom, I put the sail in front of the boat (with the mast topper installed). I nest the bottom of the mast right next to the mast holder against the AKA bar, and walk the mast vertical. Once vertical I lift the mast and slide it into the mast holder. I then grab the rear stay line and clip it to the rear lifting cleat. I then run my jib halyard thru the cleat and hoist the jib up the halyard, (it actually doesn't take much longer than normal (without the jib or mast topper), basically no matter what you do you have to raise the mast anyway (lol).
When done for the day I furl the main, furl the jib (mine has a mast) and just let the jib lay down in the boat, I never remove anything from the boat (jib remains attached at the front along with all of its control lines). After droppin the mast I also lay that on top of the boat (lengthways). I take the mast topper and fold the two 3/8 tubing pieces in half and just throw the whole mast topper and all it lines into the boat ( I leave all the lines connected at the front bow). Everything is then strapped down and tidy for the next time I go out. I never remove anything from my boat, including the motor, anchor system, all the sails, and rigging. My spray curtains are double duty, when not being used, I fold them over the bow of the boat (in the forward hatch area) and the spray curtains protect everything from the highway wind, and keeps all the ropes and sails bundled together (it's actually a pretty nice setup).
If you can attach that H16 jib in a similar fashion to the way they are attached on the H16, this will help you a lot. For it to work properly, I think most of the force on the clew needs to be downward (trying to run the jib with a sail control line similar to the mainsail will not work (on the main the sail control line runs back to the back of the boat at a very shallow angle, this won't work on the cat jib (steeper is better)), you will need to develop a happy medium with trial and error (your breaking new ground here).
Hope this helps you