The motivic $S^1$-stable homotopy category $SH^{S^1}(k)$ (where $k$ is a field that is often assumed to be perfect; yet one can probably take quite general base schemes here) is "intermediate" between the unstable motivic category $H(k)$ and $SH(k)$, and it appears to be rather "unpopular". What are the main references for it and for Quillen model structures underlying it? I have only find a mentioning of one model in Morel's "An introduction to $\mathbb{A}^1$-homotopy theory" (after Definition 4.2.2) and I don't know how to "work" with this definition.
One can probably define $SH^{S^1}(k)$ as the localization of the homotopy category of the corresponding spectra of simplicial Nisnevich sheaves (since the latter category is cellular); however, did anybody write this down before me? This approach is also related to the study of the functor $H(k)\to SH^{S^1}(k)$; cf. Connecting Quillen functors between motivic homotopy categories (of different "types"): references?