Been a while since I did my Kombi conversion and had to drop the diesel tank to fit the plates for mounting a single seat on the nearside which allowed access to the nearside bolts but to access the ones on the offside was going to require removing heat shielding and various undertray parts which became a PITA so used a disc cutter to remove them from the top side. Obviously destroying the brackets in the process but much easier and an option if you’re not wishing to keep the mountings.