Re: unstable 10 ft. aluminum boat!
Ahh A subject I know a little something about! Forgive me if I get longwinded.
You could rig a pair of PVC pipe outriggers on her, or something like this
http://homepages.paradise.net.nz/garyd/quikama.html but there is really no substitute for balance.
Personal balance. Once you get the hang of it, it is much like riding a bike.
And a careful choice of boatmate. (tandem bike)
I have only 2 boatmates I trust on her but I trust them implicitly. We almost instinctively counter balance each other just by feel. Even a bit of beer drinking or standing are little problem.
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Until you get that experienced, low and slow! Stay low, move about in the boat slowly. No jerky or sudden movements.
Warn your boatmate before you make any movement more involved than scratching your nose. Yep, if you need to lean up and scratch your butt, you need to announce it first.
Be careful about leaning over the side to land a fish or what not, if you start to take water it can go badly very quick. It takes less water than you think to blow the balance (yours and the boats) leading to taking even more water,,, over and down you go.
Other handy tips:
If it needs to stay dry, ziplock bags. Leave some air in so they float.
If you don't want to loose it, when it is not in use tie it to the boat. Doesn't take much, string is fine.
Watch the Weather!! Not just the forecast, keep a weather eye out at all times. Even just a stiff breeze sneaking up the river or across the lake can get serious if you are surprised..
Be careful how much gear you take or mount, mine is rated for 300lbs---Gear and people. Not much leeway for extras.
Need I mention the wakes from larger boats?
All of these were learned the hard way.

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That said,, I love my little 10 ft Jon. Had her for 20+ years.
Just a couple inches of water and she floats. Handy for getting into back waters and down shallow streams/rivers.
Calm day and she can float out on the Ohio River. (yes, as matter of fact, I am nuts)
I have even slept on her.
But she is what she is, not much more than a beer can, you have to learn to work with the limitations.