Hi and welcome.
I am in the Ozarks in Missouri, and yes, there is a lot of older relics to be found. Research is the key to finding the spots that you may want to hunt. There are many routes and techniques in researching this area, but here are a few tips that might help. Feel free to PM me as I might be able with specifics (at least in Missouri research).
1. Study Sanborn Maps of the towns that you want to hunt in. They will show exactly what buildings were there, what they were used for, etc. The Kansas City Public Library offers a free library card to KS and MO residents and they have access to both KS and MO Sanborn Maps.
2. Check locally and online for Civil War information. Maps, battles, skirmishes, "bushwacker" raids, border raids, camp sites and much more has been documented and is easily available. Plotting the information on old maps and then transposing it to modern maps is time comsuming though. Be warned.
3. Read old local newpapers. Many spots can be found that way.
You said that you are on the Santa Fe Trail. There is a lot of documentation on the Santa Fe Trail. You are undoubtedly near outpost sites, camp sites and much more.
Basically, find a subject and read, read and research. I will spend weeks, months, and in two cases years researching, trying to find both good sites and potentially virgin sites. That is part of the fun of this hobby for me!
Keep at it and you will find the goodies.
Doug
PS - If you want a quick fix for oldies, find a patch of woods or a pasture that you can get permission to hunt. If you go out and hit them, you will undoubtedly find 70-100 year old shotshell heads, bullet casings and possibly more.