Portable fishfinder for slowly navigating shallows

[Ribbit]

As I am going to be single handed, I'm going to be at the wrong end of the boat for keeping an eye over the bow while steering into lots of unknown areas.

So I thought it might be an idea to pick up a small fishfinder like the Lowrance Elite 3X, which has a 20ft lead, and also has a 15ft extension lead available.

Now if I mount the transponder onto alumin(i)um tube, I figured it wouldn't be difficult to fit a couple of mounting brackets/clamps on the pulpit, and have the transponder facing forward at about a 45 degree angle (flat would be nicer, but 45 deg should give more advanced warning), then run the cable back to the steering position and the display.

While the 15ft extension would probably still be too short, it would be easy enough to patch any necessary extra length into it.

As I like fishing as well, having the setup portable rather than fixed would be nice too (plus avoiding putting holes in the hull, which I am not a big fan of).

Sound a practical and worthwhile thing to do (not exactly expensive either)?

Related to this, would a fishfinder with CHIRP offer any advantages over the standard transponder type (I'm not worried about that sort of detail just for fishing)?

I know off a transom mount, the transponder is usually just in the water flow, but could a couple of feet extra depth off the bow be more useful for a navigation purpose?