There's more to go on here than in a lot of cases, but we do have to be careful not to assume too much. I'm sure many thousands of hours have been expended trying to chase down French Canadian possibilities.
Colorado Springs is where the Air Force Academy is located, and a large number of Air Force personnel are posted there or retire there. It could mean something, but maybe not. Anyway, although her family is from MN, she is reported missing from there in '75. It's a long time to keep your family guessing, which suggests that maybe there was a reason she didn't want to be in touch, such as a guy.
But in this case, the guy is reported missing, also in '75, but from his hometown of Lancaster, PA. He's about 30 by this time, and he's a guy, and he's ex-military, but his family are still concerned enough to report him missing. And as Carl likes to remind us, this is all--both of them not entered in NamUs before last year, when genetic genealogy had offered them up as possibilities and their status as missing was entered on our accessible databases--a good reminder of what an incomplete picture of missing persons we have available to us on the web. Now, does he go out west, and meet her there, and travel across the country? Sounds romantic, and maybe they head south to AZ, go to the southernmost of the three truck stops represented by the matches, and travel east until they get to SC. Or, maybe not. Maybe Jim gets the matches from a truck driver or someone who's staying at the KOA, assuming they ever were there. At any rate, LE seems to have reason to believe they met each other hitchhiking, and maybe someday we will find out why that is, or what other suspicions they may have regarding PsOI. And it's just as likely that she hitchhiked and he hitchhiked and they fell in together close to where they were murdered.
Robbery doesn't seem to be the motive, if the watch and jewelry are still there. Presumably, though, they would have carried some form of ID, so it's likely that was removed to make ID more difficult. There is some speculation that they may have had a vehicle, and that it may have been stolen, but in that case now that we have ID investigators stand a good chance of finding out whether either had a car registered to them. And I'm going to guess no, because if Jim's family were posting ads regarding an inheritance, there's a good chance they may have hired a PI to run down at least Social Security and car registration records.
So, maybe we will get enough information to speculate intelligently on the circumstances, and maybe not.