There very easy to change from soft top to hard top I done my ex military 90 last year hardest part was getting the spare wheel cradle to sit right, that took a few hours
What you need to also ask yourself is can you get landy parts quickly for we it goes wrong and it will at some point . Can you get all size tyres out there if not might be worth not getting larger tyres get a more bog standard size if there more available or take a another set with you as back...
My abs light come on and off and like you done the blink test and says a air gap , I just keep knocking the sensor back down. I have been told that if I take a shim out it would solve the problem . Did you manage to sort the problem