I don't know exactly your scenario but why do you want to use NAT?. The original packet from your private network is encapsulated in the IPSEC tunnel and arrives to the remote netwok with the same private IP address that in the local address. The only think you must do is to add routes so that one network know that the other one is through the router 26XX.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...