Yup RM, that's how it began for many kids and how a solo Class 4 Challenge can be done in relatively good comfort, seaworthiness (when properly fitted), and speed. With plenty of room to sleep right in the boat under a boom tent, there's no need to feed the raccoons or skeeters -- just anchor out. And the Blue Jay is a classic -- the younger/smaller sister of (trainer for) the iconic 19' Lightning also designed by Olin Stephens -- one of America's greatest "yacht" designers. Rig her right and with her hard chine, she should even go to weather in <1' of water.
KB, I've never seen a gunter-rigged BJ -- but don't write it off, yet. There are good reasons why it remains a popular rig in UK/EU even today. If the your boat's rig doesn't work well, the sail could be a big part of the problem, and the PO's setup may be flawed, making it hard to rig/set/reef/strike properly.
You have a couple of options, depending on your budget, sailing style, and venue. As discussed above, you can return the boat to "stock", but its stock "pinheaded" triangular mains'l is not particularly efficient by today's standards. OTOH, a well-sorted gunter rig with "fat-headed" mains'l could be a good rig for the boat, with many attractive features for WT types -- most stemming from the short "fixed" mast: easier to step/unstep, fits under a lot more bridges (which may or may not be happy to open for you under sail -- you paddlers take that detail for granted
). Yet able to get the sail area "up there" to catch the breeze on those super-light summer drifter days you get in the tidewater region. And "in principle" the sliding gunter makes it easy to shorten sail or even strike the mains'l completely by lowering the yard (also reducing airdraft and weight/windage aloft). Yet helm balance remains basically unaffected. And performance of a well-sorted gunter rig should be very close to -- or potentially even better than -- that of the stock rig, while being more manageable and flexible, given that the stock BJ marconi sloop rig has no provision for reefing. This makes the gunter well-suited for a challenge-type boat, knocking about in an area where thunderstorms may pop up out of nowhere, or sailing in fresh spring/fall conditions. Here's an informative article on sliding gunters: http://www.duckworksmagazine.com/04/s/articles/gunter/
The BJ has simple 3-stay fixed rigging with no backstay, so you could go right to a more efficient, really well-sorted "batwing" or "bird's-wing" full-battened gunter sail like those in the article and that Sawhorse and his buddy Hugh Horton use on their sailing canoes. Here's an article by Sawhorse from some time ago (further developments since then) that provides some insights and ideas that could be applied to your rig: http://epoxyworks.com/index.php/evolving-the-sailing-canoe-rig-for-cruising/. The folks at Sailrite might even be willing/able to gin up the custom sail pattern for you. Or you could try modifying a Club 420 or CFJ "Power-head" (square-headed) mains'l from Intensity Sails (very inexpensive but very serviceable). Intensity's 30sf, very inexpensive Club 420 jib might work as a substitute for the stock 26sf BJ jib: 420 luff is 11.5' vs BJ's 12.2'; foot is 5.75' vs 4.26', so jib leads may need to be moved aft. Also note that the BJ jib hanks onto the forestay, while the 420 sail is set flying (not a big deal, and easier to set, but must be brought into the boat when dropped).
If you decide to go back to the stock BJ mast, you could probably use a Club 420 sail (standard "pin-headed" or Intensity's Power-head) on it. The sail area of both stock sails is virtually the same, foot on both is the same (7.9'), and at 16.1', the 420's luff is "only" about 3" longer.
One more wild&crazy idea: as the BJ mast is keel-stepped, you could rig her with an unstayed balance- or standing-lug rig...say, a commandeered Goat Island Skiff 105sf rig, or a SCAMP 100sf rig. I'm guessing she'd go pretty good and balance up about right (the swinging c/b gives more flexibility in getting the right amount of weather helm). And with no jib and no stays, dead simple to rig and sail. You can make a suitable mast from an old, widely available Laser rig (just shorten the upper to about 5'). My wuzza-Lightning Hare, originally rigged like her little sister the BJ, now has two balance-lugs'ls (or lugs'l and Powerhead Laser sail ) using this approach, making her much more comfortable and forgiving sailing solo/shorthanded while as fast or faster on most points of sail.
I'm toying with a sliding gunter setup, too, for the reasons mentioned above plus the ability to fly a jib and a mizzen stays'l (not very do-able with an unstayed balance lug). And, not least, the sleeved 90sf? Power-head Laser sail on a stock Laser mast has no ability to be reefed (we are adventurous Tribers, not round-the-buoys sailors, so we well understand the importance of reefing capability
).
Good Luck -- and Fair Winds!
DKHT
PS: the BJ jib that ZTH gifted to me is, alas, MIA.