Well, they certainly can be tilted inward.....and a suggested max tilt of something like 45 degrees. The more tilt you have, the less effective they are. The way i opted to mount the brackets on the outside of them frame, prevented me from tilting them inward, hence the cross brace that is just there for bracing and no upper mounts installed on it. With the triangulated setup, there won't be any (or very minimal) side to side movement of the rear end, and the vertical mounts of the shocks will actually provide the best ride quality. At least, that is based on the research I have done.
If that is way off base, then i suppose it would be better to figure that now
I should note also, that those shock mounts have like a swivel bearing(?)......that allows the front to back movement, which will allow the up and down without any binding. I can take the bolt out of the upper mount and rotate that shock all around on the lower mount. I believe it allows for that kind of travel.