The question about finish time does not have an answer becauese as you said there are way to many variables.

As far as the water goes:

"1. Use small rubber tubing to direct a small about of water to the plant."
- do you mean just by gravity it's going to flow? does not seem like it's goin to work to well.

2. Dig a ditch that leads the water to the plant, but stop the ditch about 3 feet away uphill so that the water doesn't flood the plant but keeps the area moist.
- Again, not to trash your idea, but I do not think it will work well not to mention the enourmous effort involved in trying.

3. Don't irrigate at all and just plant the plant within 3 ft. of the stream and allow the roots to grow down to the water table. -
- Dont plant 3 ft away from the water because of flooding, foot traffic and high risk of mold. Dig up the area and turn the soil thouroughly down to at least 12 ". Add lots of compost, water crystals and mulch on top.

ALSO - Carry extra water during dry periods if you can. If there is a water source fairly close get a 12 V rechargable battery, a marine bilge pump and some plastic marine hose all available at any boat / marine type place. Hide them in the area and use it like a garden hose when you visit. A 500 GPH bilge can be had for about $25 and will put out the pressure of like 1/2 the average outdoor hose. A single charge on a small car battery will usually last all or most of the season and you may have to recharge 1 or 2 times if you really use it a lot.