I think the best stand to hold your laptop or iPad in your lawn care / landscape truck is a Ram Mount stand.
I’ve been asked many times if we use iPads, mobile phones or laptops in our trucks.
The device we use depends on what the crew / tech / manager does in the field. Many of our trucks are fitted with (and will be for a while to come) inexpensive refurbished Dell laptops.
They are inexpensive and give us a lot of power. Most important they have a full keyboard that is fast to type on.
It is much easier and faster to type notes, call details, estimates, etc. from a full keyboard than it is from a small iPad keyboard.
We use a Ram Mount laptop stand. You can visit their site at www.ram-mount.com.
Over the years, we have tried inexpensive stands but they have not been worth it. Ram Mount stands are the best. The laptop stays still while driving and does not bounce while typing. They are very much like the stands used in police cars.
If you want to mount your iPad in the truck they have a stand for it as well…
http://www.ram-mount.com/NewProducts/AppleiPadMounts/tabid/2614/Default.aspx