Does anyone have a general idea of how easy it would be to bring an R21 or R34 to a SLAC? Is this something it would be worth asking the search committee about?
Tread lightly. SLACs vary tremendously when it comes to campus resources for research and grant support. Stronger SLACs will likely have dedicated administration to help with these things. Smaller institutions, or ones that are predominantly teaching oriented, may not have any actual administration to help with grant support. There may be a designee for these things, but the person might do grant-related activities on a part time or "as needed" basis. In this latter case, a major grant may be something they're not strongly equipped to handle. Since most institutions like the idea of grants, I'd instead ask them about "what types of support are available for faculty who want an active research program involving undergraduates?" Then, probe for more about admin support and examples of any grant-funded research that's been carried out at the institution.
I leave it to colleagues who've had these types of grants to comment further.