Now everyone is going to slate you for your choice of lowered and big tyres, I however wont as its your Disco and you can do what you want...
The first problem you will get with big alloys is they will fracture easy, the stress from lower profile tyres and the usually weaker design of alloy wheels don't go well with big heavy cars.
As for lowering, springs is the secret, you may need to get them custom made, I advise strongly against cutting them as the spec will be out and on a 2 ton vehicle it will make a big difference. You need to find out corner weights and standard spring heights first.
I would advise against lowering if your towing however, maybe HD springs that will stiffen it up but lowering will cause issues with rubbing e.t.c. when you start adding weight.
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If you want a lowered tow vehicle that has 4WD get an Audi All-Road, a Disco is a bit much to lower...
I can vouch that the Audi Allroad is an amazing vehicle as I bought one nearly 2 weeks ago, but I suppose it depends on what you need it for and how you will treat it and your budget.
The Landy is far superior off road due to its articulation and the fact Im not fussed if I scratch it, also I can chuck a couple of muddy kids and wet dogs in the back without caring. It has more space inside for lugging things about, I do however have to "drive" it and long journeys can be tiresome. You can just about fit 7 adults in (petite chicks in the back

) You can usually fix them for about 20p. I paid £1700 for mine 4 years ago. Its my ruff motor lol.
The Allroad has 4 different ride heights so you can go from low and aerodynamic to 5mm more ground clearance than a standard disco at the push of a button, as it is on air suspension the ride is comparable to that of a Range rover but with the road plantedness that the Quattro system provides. It has enough space inside with the seats down to transport a fridge freezer 2 adults and a weeks shopping with ease. It can handle average green laning/light off roading with surprising ease if you dare (only "car" to have successfully completed LRs test circuit) and is great in the snow (with the right tyres) manual ones even come with a low range box as an option. Its designed to eat up the miles and I find I generally just point it in the general direction of where im going and it effortlessly drives itself, I can do 8 hours and get out fresh as a daisy. You can comfortably seat 5 large adults and 2 children. You could get one for £3500 and you get a lot of car for that money. They can be quite expensive if they go wrong. Its my posh motor wotwotwot.
Both tow brilliantly (Landy can prob tow more), both return similiar MPG (Audi 28-33) (LPG V8 26-28?) both similiar weights and sizes (Audi 15st lighter but wider and longer)
If you still want the lowered Landy (different horses for different courses) Ive seen -1" and I think -2" springs on the internet, Im sure they would stiffen up the ride and hopefully make it handle better due to the lower center of gravity. If I ever change wheels I never buy aftermarket, I always go for Factory originals so the vehicle still looks "factory/stock" If you try to buy newer/larger alloys for example off a disco 2/Rangie etc you will end up having to spend a lot on spacer/adapters to make them fit (+20 new wheel nuts).
Heres a pic of my new baby on ride setting 1 and 4 (lowest and highest), note my feral boy on the LandRover: