Here is what I tried this summer and it is working good. This is crossing a shallow river about 300 yards bank to bank.
I already had a support wire over head {two strands of barbed wire} with wires hanging down to support a electric fence tape. this has lots of drop in so it is strong enough. Been up over 20 years. one end is on a pole, other end is hooked to a post about 50 ft above the river. I previously used electric fence tape supported from this wire. It was often taken out.
This year I strung another barbed wire insulated at both ends and from the support wires. this was just low enough that I could still reach it from standing in the river. From this wire, I tied on pieces of electric fence tape that hang down to about 18 inches above water. the barbs keep these pieces of electric fence tape from sliding on the wire. These are placed about every 10 inches. from a distance, it looks like a wall. when the wind blows, the ends do get high enough that cows could walk under, but they see the tape fluttering in the wind and they already have a healthy education of what that stuff is. they so far have not got through it.
It stayed in all summer, haven't went to look at it, hope I didn't have the tape to close to the water that the ice built up and froze it in. I will be doing 2 more of these next summer.
To support the end of the insulated barbed wire that ends up in the side of a hill, I screwed in one of those screw anchors sold for fence corners.
This is hooked to a 6 joule fencer, so cows have a healthy respect for it.