There will be two big problems with trying to attract any volunteers to help with any of this stuff at Tailem Bend:
1. The location. Country areas may have a higher rate of volunteerism in general but that's still going to work out to a lower absolute number than in an urban area, and an even lower number who might be specifically interested in a railway project - therefore the volunteers would have to come from Adelaide. People volunteer with railway groups because they love rail stuff, not because they've woken up one morning and discovered they have spare time they just have to fill it with something (the cabals of musty old fogeys building their little empires at rail groups would deter any casual volunteer).
2. The lack of credibility. The NRM, Steamranger and Pichi Richi have well known names and reputations established by industry/government affiliations (the degree of which has varied over time) which provide something that a potential volunteer can aspire to be a part of carrying forward.
In contrast, here all we have is a bloke called Steve (no organisation name, let alone one with the mendacious inclusion of grandiose words like National or Steam) with a handful of pensioned-off carriages rusting away in a nondescript weedy yard and no clear indication of what common purpose people would be working towards. Would it be the establishment of a new museum, operation of tourist trains, doing them up to sell them as crew cars, or is it simply a bigger version of a "project car" appearing in the shed to tinker around with during a mid-life crisis?
Combine the two, and you can see why it would probably be hard to convince a rail enthusiast looking to volunteer somewhere to keep going past the Mt Barker exit if they took a trip up the freeway. There's a lot of hard work to be done before things get to the point that the theoretical Steve Association might be able to attract volunteers.