Multiple overlays

Is it possible to add multiple layers of overlay? It doesn't have to be done by user interface I can edit providers.xml. Usecase:
- layer with tiles/squadrats with 30% visibility,
- layer with Strava Global Heatmap with 100% visibility.
Both of them works like charm separatelly but it's hard to switch them while riding bike and I need heatmap especially in difficult terrain when a GSM reception is quite erratic. So changing overlay in that moment quite often is not possible. I'm using v3 but if it's possible in v4 I'll gladly change it.