Help needed: VPN inside Wi-fi bridge

Hello I am in this situation:

HQ: Two internet connections, redundant each other.

#1 Shdsl Line - Cisco 2651XM 48F/128D IOS 12.4(19) advsecurity + AIM/VPN/EP

172.16.0.27/27 (dmz side ip) #2 Adsl line - Cisco 837 12F/48D 12.4(16) ios if frw plus 3des (the complete one) 172.16.0.28/27 (dmz side ip)

Remote site: One internet connection #3 Adsl line - now C827 (12.4(8) IP FRW) - will be replaced by C837 12F/64D

12.4(16) ios as above. 172.16.0.29/27

Since C837 and 2600XM with AIM/VPN can offload the ipsec/3des via hardware, I am planning to do one Ipsec/3DES vpn site-to-site. I have one /29 public ip range that if one of my lines dies, it statically route on the connection #2 and then #3

The HQ and the Remote site are connected wireless via two Cisco BR350 bridges (Bridge HQ 172.16.0.21/27 - Bridge remote site 172.16.0.22/27)

So we have:

HQ: Line #1 (.27) Line #2 (.28) BR .21 ------------>