wow any ways if you still give the wood idea another thought i cant find a picture on my laptop might be one of my desktop but i drew a quick little picture showing you how its built.
you can make it 2 feet or 4 feet wide what ever you have room for or feel comfortable hitting with the MTs (mine was 4 feet wide)
here is what youd need (about 20-25 bucks and an hour to build it)
(1) 2x8x8'
(1) 2x4x8'
(1) 2x4x12'
(1) 4'x4' 1/4" piece of plywood (i used 3/8 but itd be lighter using 1/4)
(4) 1/2" bolts 4" long
(4) 1/2"wing nuts
(8) 1/2" flat washers
you can see in the picture that you cut the radius into half the 2x8 for each side, and use the 2x4's as joist with the left over 4' piece of the 12' board going to the Legs that are bolted on with the 1/2 bolts and wing nuts.
if you only wanted it 2 feet wide just leave out the 2x4x8' and youll only need a 2'x4' piece of plywood.

very fun ramp , i need to build another i ran over mine with my F250 on accident about 6 months ago and it ripped the screws out of one of the radius' and broke one back leg.