Casting long leader into the wind
A question was asked on another forum about how to cast a hopper on a long tippet into the wind. The guy who posed the question was using a 13.5' 6:4 rod, 15' of size 4 or 4.5 line, 6' of 5X nylon tippet and a big bushy hopper. It worked for him with no wind or wind at his back, but not into the wind. He did find that a small beadhead nymph would work into the wind with that line/tippet combination. With the hopper, he could get the line to lay out, but not the tippet.
The two answers that I thought were the most helpful suggested (1) using a twisted fluorocarbon line instead of a level line and (2) using a tapered 3X, 4X, 5X tippet instead of 6' of 5X. Both suggestions will help. The twisted fluoro lines are heavier than level fluoro and the greater mass, together with the taper, will help cut the wind. However, he will still have problems getting 6' of 5X to turn over when casting a bushy hopper into the wind. Starting with 3X will definitely help the tippet turn over, but probably not enough.
His problem illustrates one of the limitations of traditional (pure) tenkara, in which roughly 3-3.5' of relatively thin tippet .006" is tied directly to a relatively thick line .013 or .014" in his case. That set up works well enough when making short casts with a sparse wet fly on a windless day. Plus, it is the ultimate in simplicity. When the following changes are made - twice the tippet length, large bushy fly, windy day - the system stops working. Years ago, I found that a short section of hand tied taper between tenkara line and tippet would help a dry fly turn over. Since then I have mostly fished wet flies so I have adopted the abrupt but simple line to leader connection.
Because he is fishing a big western river, and because big fish in big western rivers like big hoppers, we'll assume he wants to keep the length of his line plus tippet the same at 21' and that he still wants to fish a big hopper. He did not say whether he was using twice the usual tippet length because the fish were put off by the colored line or because a longer tippet helps minimize drag. (The traditional tenkara approach to minimizing drag by keeping all the line off the water fails to work in the wind because the wind catches the line and creates even more drag.)
My suggestion would eliminate the huge difference in line and tippet diameter, and effectively blur the line between line and tippet altogether. Rather than starting his tippet at 5X as he is doing now, or even 3X as suggested, I would start with 0X - which is the diameter of size 3 tenkara line and is the diameter I use as the first step down from size 4 line when making my hand tied tapered tenkara lines. Because he absolutely needs as much transfer of energy as possible, I would suggest stepping down only one X size at a time, going from size 4 line to 0X, 1X, 2X, 3X, 4X and then no more than 18" of 5X tippet. At minimum, I would use a 0X, 2X, 4X taper, which is the one I used early on with dry flies, but that was for a shorter overall leader* length. I think the more gradual taper would be better for a 6' leader*. For that matter, with a big bushy hopper, he could very probably get by with 4X. (I wouldn't suggest 4X with a light tenkara rod, but the rod he is using could probably handle it).
*I have seen remarks online that suggest anyone who refers to a tenkara line as a "leader" does not know what he's talking about. The pure tenkara line-tippet construction, which goes directly from line to tippet, does not use a leader, but my recommendation outlined above does. The tapered section from 0X through 4X is not really part of the line and is not the tippet. It is in fact a leader.