Rackwise, I know a South African guy who has a full rack on his Hilux, but its from SA. I can email him for the details if you want?
Showerwise, Ive tried a few ideas.
1. 5 gallon plastic drum (strapped to roofrack) with hose and watering can rose attached to tap - perfectly good esp in hot places where sun heats water up. Not that tough but easy to fix and replace. Vulnerable to bugs living in water unless you puritab (or similar) water first.
2. "Solar shower" black plastic bag with hose and tap, similar to above but purpose-made, about 20 quid at Billing. Fine, same limitations as above.
3. 12v electric goldfish tank pump connected to shower head. Drop pump (plugged into fag lighter) into jerry can and instant shower. If can has been on roof in hot area, instant warm shower. If used in UK, will stop traffic (eg in Ben Nevis car park in March)
4. Brownchurch shower/filter combination with built-in heater. Fab, but pricey and not overly robust.
5. Twine heat exchanger system - hot water on demand. Very civilised. Not cheap. Get one
'91 LR 110 Def/Disco hybrid "Elsa"
Bring me the horizon....