40 peers is the max you cna have. Are you sure you really want 160 backup peers, that doesn't sound right?

I think what you want is 160 peer routers catering for 160 sets of encrypted traffic. By putting all your peer routers under the "1" instance you saying that the second is only ever used if the first is down, the third is only ever used if the first and second are down, and so on. Is this what you want?

Or do you want to encrypt traffic from A to B to peer 1, traffic from A to C to peer 2, traffic from A to D to peer 3, etc. If so then you need to do it like this (note the different instances of the same crypto map, each pointing to a different peer with a different access-list):

crypto map 1 ipsec-isakmp

   set peer 1.1.1.1

   match address 100

   set transform-set esp3des

crypto map 2 ipsec-isakmp

   set peer 2.2.2.2

   match address 101

   set transform-set esp3des

crypto map 3 ipsec-isakmp

   set peer 3.3.3.3

   match address 102

   set transform-set esp3des

......

access-list 100 permit ip

access-list 101 permit ip

access-list 102 permit ip

......