Trolling with extended leaders without large downrigging gear is what LongLiner does.  Suitable for lines and leaders from 6# test to 60# test (up to 125# test in spectra lines), LongLiner is a valuable tool for small and large boats, including  kayaks. LongLiner allows long leader presentations at controlled depths delivering a short leader when landing a fish, when control and a short leader is best.

Some call this "the tackle box downrigger."  

Weight attachment options include two products: Weight Hanger and the Bottom Skipper on this site.

Go to video links below for more information:

Videos

Rigging Instructions in video format:

https://www.youtube.com/watch?v=0IBqDmiqKIY  and,

https://www.youtube.com/watch?v=u87TG4C8dxU

My other video demonstrations:

https://www.youtube.com/watch?v=TwuK6OICuTg

http://www.youtube.com/watch?v=cjeBPkfD-9E

http://www.youtube.com/watch?v=cyztY0aQk5U

Kayak Angler Magazine:

http://www.kayakfishingmagazine.net/gear-guide/91-new-kayak-gear/1150-longliner-for-deep-water-kayak-fishing.html

More information on the LongLiner® (pdf's for download):

Big Water Salmon and Trout

Depth

Fishing Large Rivers

Rigging Instructions

Trolling and River Apps

Field Report 1

Field Report 2

Trolling for Large Trout