Hi there,
So I've installed beadboard in my tiny ensuite,it looks great but I didn't realize the toilet tank won't fit back onto the base because of the thickness of the beadboard... so my question is,should I get a new toilet with a 'skinnier' tank or try to trim the beadboard back with my dremel?
Thanks in advance

You may be able to "wiggle" the base out enough. Loosen the closet bolts and try. However, I suggest removing the base and install a new wax ring if the installation is more than a couple of years old.

How much room do you need? Or how thick is the beadboard? You do know that once the tank is mounted nobody can see the board behind the toilet, whatif it were not there at all, who'd know?

Depending on the amount you have to move the toilet away from the wall, you can get an offset mount at any of the big box stores. You should also use a new wax ring.

Chuck