Instead of modifying the trusses, I'd open up the whole space. Trusses don't take well to "field" modification, and I doubt that the mfgr. would give you any advice on how to do this, informal or not. Besides, opening up the whole space would give you a lot more flexibility.
Here's how to do it.
Assuming the trusses are on two-foot centers and are centered over the bay where the lift is going, remove the metal roofing 4 feet to either side of the center truss. Remove the center truss and the ones on either side of it (three total). Take two of these trusses and "sister" them to the remaining adjacent trusses (screw them together every foot along their entire surface, using #8x3" galvanized deck screws).
If the plate on the top of each side wall where the rafters have been removed isn't at least a 2x8, replace it with a 2x8 and bolt it into each concrete block cell that is filled. This may be overkill, but it is intended to prevent the wall from bowing out where the rafters have been removed, hence the walls are no longer "tied" front to back.
To fill in the space, use 2x6 "purlins" (beams going lengthwise between the rafters). Place them at the ridge (peak), above the side walls, and where the short truss elements join the long elements along the roof. They should be angled so that they are perpendicular to the roof line. Fasten the purlins to the trusses with joist hangers.
Then nail a 2x4 diagonally to the underside of the purlins on one side from where the top purlin joins one truss at the ridge to where the bottom one joins the other truss at the side wall. Do the same on the other side but in the opposite direction. Again, this may be overkill, but it is intended to prevent the roof from "racking" due to the 8' gap between the rafters.
Finally. replace the metal roofing.
Now you have an 8' wide "cathedral" ceiling over your lift, along with a roof system that will take the snow and wind loads the original structure was designed to handle.