I checked my "Early Pioneers/Settlers in Valley County, Idaho, (1870-1920): An Index" and was unable to locate a Tull family. Just to be sure I went back and reviewed all of the homesteading Claims for Valley County (some 40 pages of them)and did not locate a TULL claim. It may be possible that a claim was filed for,but never "proved up".
My "Early Pioneers..." contains Surnames from the Valley Couny Index to Misc. Records, Vol. I kept by the County Clerk from 1917-1973 and including earlier court records for the period 1881-1916. I have no record of a Tull turning up in those records.
I would appreciate it if you could provide me with a copy of any documentation (family letters, etc.) which show that the Tulls were in Long Valley during the period you mentioned. I would be happy to include them in a future revision of my Pioneer compilation for the county.I can well imagine that there were a number of early settlers in the Valley who did not leave a formal paper trail.