The double Rainbow should also be well vented, and you could use the inner fabric attachment. I would think that, with both vestibules open and the inner fabric attached to create nice shade, you'd be as cool as you can get. You have to consider whether you want silnylon as shade. If you go with full bug netting, the sun can still warm you up too much. On the other hand, most tarp tents with only one opening will get way too hot in the sun. The Double Rainbow provides the cross-flow ventilation while providing double-wall shade overhead (the inner fabric should really keep the heat from the silnylon down).
With the scarp 2, if you want to use the silnylon canopy for shade, you have to put the whole thing on, which likely will become too hot.
If it's just solo use, you could also use the MLD DuoMid and inner mesh. With the DuoMid, you can roll up half of the canopy to create a 2-sided pyramid shade while inside full bg netting.
Are you concerned about blowing sand? You may want to look at a tent that fully seals up.