Vehicle Mounted Advertising

We have a metal A-Frame mounted to roof bars that we put on top of our branded company vehicle and use for advertising. We are looking for new graphics to go on the frame to promote our prescription delivery service.
The frame measures W1300mm x H600mm.
We want to keep the design fairly simple and easy to read as it drives past, while still being aligned with our brand and the branding on the vehicle itself.
There are certain key points that we would want to highlight.
They are:
That this is an easy to use service.
That it's convenient.
Some patients may be eligible for free delivery.
And our contact details.

An idea that we like is to have an image of a prescription being delivered to someone on one end, with these details next to them. This would be duplicated on both sides.
I have attached images of the frame, the van, and our logo pack.