The stock phone holder works but its a tight fit. I use BobjGear Rugged Case (B01AM8G6YI for Samsung Tab E) on all my tablets, they offer exceptional protection from drops. It affords a large soft outer lip that easily accepts a homemade sun visor. These cases have built in channels that direct the tablet's sound to the front.
That's exactly the unit I bought... there were multiple low-res tablets for a LOT less but while the solo won't care about the added resolution, some of the other tools will take advantage of it (mapping and satellite imagery for instance). Besides... I've not had any device with resolution under 1080p for many years, seemed somehow wrong to do it now.
Having said that... in very bright direct sunlight the screen is nowhere near bright enough. I built a hood and that helped some.