Whether you can Tenkara fish without harassment on fly fishing only stream will probably dependent upon how the official you have an encounter with defines "conventional fly fishing tackle". However, in WV they do not list a reel as being a requirement. So perhaps Tenkara would not be seen as verboten.
Page 6 in this adobe pdf document list the regulations for Fly-fishing only streamshttp://www.wvdnr.gov/Fishing/Regs12/regs_SpecialAreas.pdf
The same information from a non-government web site repeats most of the same informationhttp://www.wvangler.com/FlyFishingOnly.htm
2) Only artificial flies and streamers may be used or in possession on any of the fly fishing only streams.
3) Only conventional fly fishing tackle may be used. open and closed-face spinning or spincast reels are prohibited.
Item number 6, left off of above web site, but printed in the wvdnr adobe pdf document, list this additional regulation
6) No lure or fly with any scent, or oil, or editable enticement added onto, or impregnated into ( regardless if the scent is added in the manufacturing process or applied afterward), may be used or possessed on any fly-fishing-only trout streams.
I've been Tenkara fishing for about two years. When fishing on fly fishing only rivers I have yet to see or be approached by a DNR or other official. Thus, I have no first hand experience how a local official may define 'conventional fly fishing tackle'.
In deed, the first and only time anyone has approached me and asked to see my fishing license happened two weeks ago. But I was fishing a lake where it is catch and release of bass fish only. Oddly, the official showed no interest in asking about my unusually long fishing pole without a reel.