That's a "must have" accessory, especially if you go wheeling, like a first-aid kit. I have a RRS so not 100% sure the front seats match the LR4s., but I mounted mine with its bracket on the removable front plate under the front passenger seat... The plate is sturdy enough to mount the bracket on and support the weight of the bottle without rattles, and I can reach and release the extinguisher with one hand from the driver's seat in case of an emergency. Somehow, I feel better having it at arm's length when I am driving, rather than back in the trunk, you never know...

It doesn't get in the way of the front passengers legs (e.g. wife) when they are sitting there.