phoenix's fixed camber plates.

No the phoeninx ones will not fix inside wear, they will make it worse, the wheels are tilted in by an extra 0,6 degrees. I think my front wheel camber is -1,35 degrees with these.
The inside wear suggests that you have the wrong toe-in (or in Norwegian -"spissing")

I have had a set of these on my car since 2008 and I love them. my tires have not worn uneven because of these, but I had an incident last year where my wheel alignment was off after a shop did my upper and lower oil sump seals, a drive to Sweden was enough to make serious damage to my tires.

If your tires wear on the inside your wheel alignment is wrong.

This is a bit hard to get 100% since most e31's have a lot of play in the steering (box).
My car just got new front tires, and Wokkes uniball TA "bushings", this eliminated much of the play I had in my steering, just the one in my steeringbox is left.
When the alignment was done they did their best, my alignment is good, but my steering wheel is not center, and I will just move it one tooth on the spline to center it.

With Wokkes TA bushings, new tires and wheel alignment I could let go of the steeringwheel at 170kph on the autobahn.
At 200kph you could have a relaxed two finger grip on the steering wheel all the time.

Bottom line.
Should you get these, I say yes, if you get your alignment fixed they will not wear the tires uneven, you will reduce the outside wear that is more common on these cars.

As of now there are not many options, K-mac make on request, but I was not happy with the quality of the K-mac I had on my e36 8-10 years ago.
I know Wokke is thinking about something, but there is no solution yet, so it could be quite some time before the product is available.