campers often go through a evolutionary cycle of upgrade from one piece of gear to the next as they find better options - they would have saved a lot of money had they researched things well first and asked around experienced campers (not salespeople) and spent that little bit extra
12V deep cycle lead acid batteries
whilst these are relatively cheap, they are VERY HEAVY and do not last long
the long term costs will be much lower with a 12V LiFePO4 100Ah battery which is about 1/3rd the weight
HOWEVER, many LiFePO4 batteries will automatically go into a frozen state if you alow the voltage to fall below a set point and this will require a special recharge process most likey with a 240V AC-DC charger which you may not have with you - so keep an eye on the voltage!
under-powered 12V battery chargers
eskies
if you really want to enjoy your camping and you can afford $2000 for a car fridge, battery and charger you are going to be far better off than spending a lot on an esky which will be a headache and a backache
do you really want to have to keep filling up your heavy esky with ice (if you can get some), then emptying out the melted ice every day and put up with your foods floating in water - chocolate tastes terrible after being soaked in water, and then risk food poisoning as the temperature has not remained low enough?
plus, with having a 12V LiFePO4 100Ah battery, it opens up a whole range of opportunities for you such as 12V electric blankets, iphone charging, etc.
the wrong car fridge
get a quality car fridge which will fit nicely in your boot and be of adequate size for your needs
think twice about getting one with a built-in battery - they are heavy enough as they are and the battery may not be easily replaceable and not able to be used for other purposes
I use a 35L Dometic CFX fridge as it is not as tall as Engel ones and thus fits nicely under the boot blind of my Subaru Outback and is just big enough for my solo needs
the 8P, 10P or 12P family tent
seriously, you really don't want an 8P or 10P tent or bigger unless you have special needs.
these tents lack versatility and are BIG, BULKY, HEAVY, require more than one person to set up and take down and can really destroy the fun of camping
you would be far better getting a 4P tent and a 6P tent - both can be set up by one person, you can get some spacial separation from snorers by being in a different tent, and when you only need a 4P tent you have one
the 40kg tent when you have a bad back
Ok this should be pretty self evident - no employer would allow you to lift anything more than 15-20kg, especially above your head
things only get worse when you have to pack up in the rain and it becomes much heavier!
the super expensive technical hiking tent for car camping
these tents will cost $1000 or so and are great for alpine hiking but they are overkill for car campers and are likely to be damaged or stolen - you would be better off with much more affordable, heavier, more durable tents for car camping
other tents that do not match your needs
unfortunately there is no one tent that will be optimum for all needs but there are some designs which will suit your needs better than others and this means a lot of research
for example, I like to sleep within the protection of a 2P Mozzie tent which I place inside a larger standing height touring tent (much easier to control mozzies in a small 2P tent!) with a rear door and a Blockout fly so I can sleep in better, and the optimal size for this is a 6P tent (3x3m) as then I have room to walk around my Mozzie tent. If the night gets very cold, I can just place a cover over the Mozzie tent and I can keep it much warmer than my 6P tent which will always be about the same as the outside temperature. This gives me a LOT of versatility - I can use the 2P Mozzie tent at the beach when I want to relax without constant harassment from march flies or I can set it up in the shade as a break from long drives and get a power nap in far more comfortably than in the driver's seat of my car.
bulky cooking and laundry gear
bulky, heavy solar panels
old style PCM solar panel controllers
cheap recovery boards
kinetic rope for snatch recoveries
heavy steel cables and snatch blocks