Lars, as you said, the records of the Arkansas State Troops are frustratingly scarce, but I'll give you what I've managed to find out. I'm using Pearce's regimental designations, because those are the designations used in the reports of Wilson's Creek. Also, there is some reason to believe that the company designations may have changed somewhat after Wilson's Creek. Here's what I've managed to scrape together:

ARKANSAS STATE TROOPS.

Northwest Division—Brig. Gen. Nicholas Bartlett Pearce.

1st Regiment State Troops—Col. DeRosey Carroll.
Co. A—Crawford County; Capt. Charles Arthur Carroll.
Co. B—Sebastian County; Capt. Thomas Lewis.
Co. C—Johnson County; Capt. Lynas Armstrong.
Co. D—Crawford County; Capt. Powhatan Perkins.
Co. E—Washington County; Capt. T. J. Kelly.
Co. F—Benton County; Capt. Daniel R. McKissick.
Co. G—Franklin County; Capt. John J. Walker.
Co. H—Scott County; Capt. George W. Featherston.
Co. I—uncertain county; Capt. Harleston Reid Withers.
Co. K—no record.

3rd Regiment State Troops—Col. John Rene Gratiot.
Co. A—Sebastian County; Capt. James H. Sparks.
Co. B—Hempstead County; Capt. William P. Hart.
Co. C—Washington County; Capt. Samuel R. Bell.
Co. D—Washington County; Capt. Pleasant H. Buchanan.
Co. E—Sebastian County; Capt. John Griffith.
Co. F—Crawford County; Capt. James T. Stewart.
Co. G—Crawford County; Capt. Hugh Thomas Brown.
Co. H—Johnson County; Capt. Alfred Dixon King.
Co. I—Sebastian County; Capt. William C. Corcoran.
Co. K—Crawford County; Capt. Joel W. Foster.

4th Regiment State Troops—Col. James David Walker.
Co. A—[Sebastian County?]; Capt. R. H. Sanders.
Co. B—Madison County; Capt. Larkin Bunch.
Co. C—Washington County; Capt. Hugh L. Tinnen.
Co. D—Sebastian County; Capt. Cabell.
Co. E—Crawford County; Capt. John T. Humphreys.
Co. F—Washington County; Capt. Thomas Montague Gunter.
Co. G—uncertain county; Capt. J. W. Johnson.
Co. H—Carroll County; Capt. Hampton B. Fancher.
Co. I—Carroll County; Capt. John Denny.
Co. K—Carroll County; Capt. James Midleton Pittman.

5th Regiment State Troops—Col. Thomas Pleasant Dockery.
Co. A—Franklin County; Capt. John Randolph Titsworth.
Co. B—Columbia County; Capt. William H. Dismukes.
Co. C—uncertain county; Capt. Whaling.
Co. D—Yell County; Capt. Commodore S. Lawrence.
Co. E—Marion County; Capt. James R. Dowd.
Co. F—Hempstead County; Capt. Augustus Simpson Hutchinson.
Co. G—Sebastian County; Capt. W. R. Hartzig.
Co. H—Sevier County; Capt. John Gilbert McKean.
Co. I—Pike County; Capt. John Arnold.
Co. K—Union County; Capt. Ristor.

Artillery.
Fort Smith Artillery—Capt. John G. Reid.
Pulaski Light Artillery—Capt. William Edward Woodruff, Jr.