Yeah that's it, it needs to fit and do the job, but it doesn't need to be pretty.
It should go over the entire front (bullbar, everything) and can be attached with ocky straps (or something) and the bonnet as JP said (practice your hospital corners). Cable tieing is no good because you only want it on when you do the water crossing (and we're not planning on driving up rivers
). If you have an installed UHF and an aerial on the front, then you'll need to keep that connected for communicating in case of trouble
so just cut a hole in it so the aerial can slip through.
Whether you actually need to use it depends on the trips you do and maybe the weather...but if you do a trip that specifys that you need it and you don't have one, no two ways about it, the trip leader will not let you go on the trip