i have that givi plate and a touratech seat that would not fit, i know picture is standard rear seat but drilled that givi rack and moved it back 2 inches, my touratech seat fits and wife has plenty off room now, cost me £10 for a few bolts and a bit of 5mm ally.
no worries i had the same issue bought the touratech seat and wouldn,t fit that 2 inch back works wife has alot more room and still carry quite abit in the top box, glad it helped