If you're going to put decent size jumps in, make sure the landing zone is large and preferably a downslope, flat landings are
.
Something to bear in mind with your rostrum also is to have it away from the track, not as close as possible, all drivers will have a better view of the track this way, and if you put the straight under the rostrum you need it set back otherwise you're into the first corner at such a rate your head moves with the car and you dont get a good perspective for your braking point.