I run a roadshower on my FJ. If you go to their website they have a option to buy the instant hot water adapter. You can cycle it back in to worm up the water or just let the heated water come out. I don’t need it in so cal but my buddy was running the set up at the expo last year and it was pretty good
I built a system like the Everlanders. It uses a 2.5 gallon corny keg and a sous vide heater. I heat up the water and pump up the keg with my bike pump. I like that it’s portable and can be taken away from camp.