Theres two reasons i don't want to just create another tunnel for my vpses:
1. Its wasting resources allocating loads of ips from HE for each VPS
I'm not so sure about that. This is IPv4 thinking. HE.net wouldn't be offering free tunnels to everyone if they were seriously worried about running out of IPv6 address space. They need IPv6 space for their paying customers too. Honestly, 2^128 is an awfully big number.
In fact, if you built a new tunnel to HE.net for each VPS host and just used your assigned /64 for each tunnel then you would be using far less address space than if you took a /48 on your first tunnel and re-routed bits of it to your VPS hosts. So unless you have more than 32,768 VPS hosts using a separate tunnel to HE.net for each of them is actually a more efficient use of the IPv6 address space. (Two /64's per tunnel, one for the tunnel itself, and one for your routed /64. Compared to the 65,536 /64's in a /48.)
2. I want the ips to be in the same range, e.g. 2001:470:89ae::/48 instead of multiple /48s or /64s
I guess this makes sense if you need to write firewall rules that encompass all of your VPS hosts. But unless we are talking about hundreds or thousands of hosts and not just 10 or 20 I'm not sure what the advantage would be.
I do have one VPS which has native ipv6 but only has a /96 ipv6, it'd be hard to allocate them to others
That /96 leaves you with 32 bits to break into additional networks via subnetting. That's as much address space as the entire IPv4 internet. (its actually more if you consider RFC1918 and other reserved IPv4 blocks like multicast and loopback) So you have more than enough room to split your /96 into smaller subnets and route them to your other VPS hosts via tunnels.
Is there a tutorial on how i could route a HE assigned ipv6 range into multiple /96s to external vpses
What operating system are your VPS hosts running? HE's site provides examples of how to setup a 6in4 tunnel on most OS's including Windows, Linux, OSX, BSD, Solaris, and Vyatta. So you could probably use HE's example as a template to build 6in4 tunnels between your VPS hosts.
But no, I don't think there are any such tutorials as people generally just build a new tunnel to HE.net since its easier than messing around with re-routing bits of one of HE's /48 ranges.