so I can free up space in the 90 its a H plate
There is your first problme!
To carry all of the spares a land rovers requires for day to day running you need a 110 as a minimum
Being an H plate I am assuiming you have the underseat tank so filling the seat box with tool sis out of the question? I would still try and fit as much into the vehicle as possible before looking to mount things onto it. as stated above water will get into it no matter how well it is waterproofed.
There is a lot of space behind the seats between the bulkhead. I have jump leads, tow rope, breaker bar, bottle jack, hatchet, bow saw, entrenching tool etc behind there. So you could fit a lot of the gear you have listed tidily behind seats.
Fuses and tyre valves live in the ashtray in the centre of the dash top.
Spare parts live in the battery box (alternator belt, lift pump, fuel filter etc) you could also fit the speedo and bonnet cable in there that you carry (although if you convert your bonnet release to a series style front mount one or loop the release cable through the grill rather than into the footwell you will not need to carry this as they will no longer beak)
All that leaves you with to find a home for are the oil itself and the spanners/hammers. I have these in the underseat tool box because I have a 110. But depending on what you have in the back of yours one of my friends has removed one of the rear folding seats (leaving three) and has a nice single jerry can holder with an open box next to it which he keeps his socket set and haynes manual in.
If you have and use all of the rear seats you could store things behind them between the seat and the tub side. On mine this is where I have more tow ropes, ratchet straps, jerry can spout, umbrellas etc. There are lots of large spaces to be utilised in the interior of a defender before I would consider mounting things outside where they need to be properly weather proofed. Things need enough weather proofing inside without adding more!
