过点P作PE⊥AC于E,PF⊥BD与F,连接OP,
∵四边形ABCD是矩形,
∴AC=BD,OA=OC=12AC,OB=OD=12BD,∠ABC=90°,
S△AOD=14S矩形ABCD,
∴OA=OD=12AC,
∵AB=8,BC=15,
∴AC=AB2+BC2=289=17,S△AOD=14S矩形ABCD=30,
∴OA=OD=172,
∴S△AOD=S△APO+S△DPO=12OA•PE+12OD•PF=12OA•(PE+PF)=12×172(PE+PF)=30,
∴PE+PF=12017.
∴点P到矩形的两条对角线AC和BD的距离之和是12017.
故答案为:12017.