Thanks for the info! I sorta' thunk that would be the case with mounting it from those bolts. I suppose it might be the reason the pretty one is so short/narrow, as increasing the square inches increases the lateral force seen by the screws.

So far I see:

1) Mounting with a bottom strip screwed to the deck between the roll bars and reinforced with Velcro to the roll bars like a Cub Scouts' compass (Chrysler).

2) Cantilevering from small screws about 1 foot from the vector of force like holding up a sign in a high wind. The 3/8" thick Acrylic would help stabilize the "flutter" a bit, but making it bigger to be more effective would offset that gain.

A question arises: What would be the problem with mounting it permanently from the roll bars themselves in some manner other than Velcro straps? Would three 1/4-20 tapped holes in a triangular pattern compromise the safety of the occupants in event of a rollover?
I'm 6'3" and my head sticks above them 3 inches already. Instant lobotomy!

I'm going to play with standoff materials (anodized aluminum?) and probably use SST Button Head Cap Screws to attach it.

I'll be pondering this while I finish tiling my bathroom this weekend...