A jet outboard looses about 30% of the hp (at the head). So a 30 hp outboard when converted to jet, will put out about 20 hp at the foot (ie where the prop used to be). Almost all jets are built on standard shaft motors (ie 20") and even then may require a jackplate or transom work to get them elevated to the right height. Heavier than a prop (for similar output hp) and higher, usually means more stress on the transom. Stronger transom is usually in a heavier thickness of aluminum boat.
A prop (especially an older 2-stroke on a 15" shaft) outboard is a good option if speed is not too critical, especially as your learning the river.
With either power choice, I suggest you motor upstream and then drift back to the ramp. Things happen, water levels could change, motors could break etc, heading back upstream is never a sure thing.
For me, the smallest aluminum jon I would go with is a 16' with 48 wide. Any more narrow or smaller is just too tippy (14' would be okay if you go with only 2 light people). The 10' and 12' jons just don't cut it for me. If you want something that size go with the gheenoe, much more floatation. Although glasswork is messy, it is much easier to repair than welding aluminum IMO. Easy to operate a gheenoe and fish while solo too.
With both boats anything over 5 hp should push you upstream at most flow levels. Larger planning area equal shallower draft and less hp needed. Increase in hp will just get you upstream faster.
I don't have enough experience with Arkansas/Supreme style jons, but understand that the long boats draft shallow and require very little hp.
Golsn.com has lots of "caney" boats. ps my riverhawk/gheenoe is listed on there too