In need of advice.

The only problem with going down the (cheap) Jimny route is it will be very easy to over spend far more than the cars worth and if you go down the custom modified route then you will devalue the car thus making it difficult to move on should you need to sell it unless all the mods can be reversed easily.

A big problem is people over modified their jimny's to the point it's not fun to drive any more, it looses its puppy dog feel. Then they want to sell it with 10k worth of mods thinking it's worth 10k more then standard.
But it's not, you might only be able to get 2k more for all your mods.
Some people buy the car and love it, then have modified and just don't love it any more to drive, only to look at.
That's why I always advise people not to modify like everyone else does, but to modify it it suit their needs and use, and not to go over the top when they do it.

I get the don't modify arguments it's expensive and devalues the car and maybe makes it worse as a car which is why temeraire is passable as a standard ish jimny. But I wouldn't be doing this for anyone else's benefit and certainly not with an expectation of profit. It's also worth mentioning that a soul would have modified parts too like suspension wheels and tyres and a remap.

I've modified a heap, lost 20k when I sold the last one, but I know that going in for the previous ones.
But for what I was doing at the time it was brilliant, for serious off riad driving it was next to unstoppable, but it did suffer on the road.
Modifications can be brilliant, but only if you will use them, otherwise they are a waste of money and will hamper the on road performance.
It can also cause a lot of problems for the new owners come time to change the rego over.

Just been doing a bit of ready reckoning and the jimny is probably going to be around 5k, the modifications suit around 3.5k, plus 1k to get it on the road tax mot insurance. Obviously the modifications don't have to happen in one go and 5k on a jimny is no guarantee of not needing roadworthiness repair. Half the same purchase price gets you a soul that is about 5 to 10 years newer more if you don't mind a few miles on it and then the modifications budget is about the same.

For what its worth, when I did a lot of work in the States, I made a point of renting as many different vehicles as possible. Tried to get a Smart in Texas as a joke.. failed. I rented a Kia Soul many times simply because I enjoyed the driving experience. Compared to what?.. Jeeps, land rovers, toyotas etc... It worked well for me in Colorado (mile high / Rockies), and I have seriously considered getting one as a run-around in the UK whilst my Jimny has heart surgery. So my 2-cents advice would be go rent one for a few days and use it as your daily driver, you wont get a Jimny style smile, but then you wont get a Jimny style sore back either!