I've had my R1T since April. I live in Texas so lots of sun. The smaller instrument panel screen, which is the object of the OP's concern, actually isn't really affected by the lack of an overhang, at least not in my experience. However, the center screen is definitely impacted by glare, especially the half of the screen furthest from the driver. I purchased the Screen ProTech matte protectors. They are not the answer to glare. In fact, I'd say that they may make the situation worse. When sun hits these protectors at the right angle, the screen becomes totally illegible; the same situation might exist without the film in place, but it certainly isn't remedied by having it. Also, the matte protector I have also tends to really show "touch points" after awhile, especially on the "button" areas that are tapped often, like the Nav and Music icons. These films were expensive and while they may add some accidental scratch protection, I'm really not sure I'd buy them again.
I also purchased a reflective screen for the roof; it is supposed to stay in place with suction cups (it has probably 8-10 if I recall). This was supposedly made specifically for the R1T. Unfortunately, it is ever so slightly too large. And while it's not meant to be left in place while driving, it's also unwieldy to take it down and stick it back up each time. I leave it in place. It tends to droop after awhile so I just periodically make sure the suction cups are firmly attached. I opted for a gold reflective surface and a black interior side; unfortunately, the suction cups have small white rings that hang down to make for quick removal...and these are unsightly since they're white instead of black. I can't recall the brand but it was advertised here on this forum much like the screen film.