For the jib tack my preferred setup is a long D shackle with captive pin and a pair of holes for a retaining wire. The bow of the D is fed through the grommet on the sail, then SS wire is fed across the opening (strung between two small holes in the middle of what would be the "top" and "bottom" parts of the letter D shape. This wire prevents the shackle from coming off the sail when not rigged. (Having the holes to anchor the wire is nice, but not 100% essential) The straight portion of the D would be a captive pin. There are any number of designs for that, I'm using the kind that has a little "nub" at the end of the pin that fits through a small slot filed into the edge of the hole and locks with a quarter turn.
Something like this, although that one is probably overkill (and it has a nice pin instead of wire).
http://www.fisheriessupply.com/ronstan-halyard-shacklesMine looks more like this, but w/o the fixed bar (otherwise I couldn't fit the shackle through the sail grommet). Instead of the bar, I just have the holes where it would mount and string a bit of wire.
http://www.fisheriessupply.com/race-lite-ss-small-boat-rope-halyard-shacklesThe same supplier also carries locking pins that might work for your mainsail tack. (My gooseneck fitting has a captive pin that would not be easy to replace, but I've seen fittings where it would be possible to just use a locking pin (the kind with a little ball at the end and a push button to release).
What I am thinking of is called a "fast" pin:
http://www.fisheriessupply.com/qrp-inc-r-style-fast-pin.
There are other types of pins that do not lock positively, but that may be fine for the purpose (and would be cheaper).