I have over 60 routers on the network between the two. What I was thinking was running iBGP on the same AS between the two routers over the network. Then peering with the upstream and try to watch the load balance over the gateways. Does this sound more like a solid plan?
Absolutely, yes. When you say that there are 60 routers *between* the two BGP routers - you will need to make sure the two BGP routers can see each other and neighbours - this may mean a VLAN or tunnel depending on your specific architecture.
What I was meaning by preferred gateway is....
Upstream 1 ---> RTA ---> RTB ---> RTC ---> RTG
--------------------------------------------|---> RTD ---> RTF ---> Upstream 2
The default route that RTG has currently is RTC then RTC has a choice ok send traffic to RTB or RTD. BGP will have a full route table on both RTA and RTF.
Okay. You also want to make sure that if one of the border routers dies that the routers will "failover" to using the remaining router/connectivity.
I will have OSPF redistribute BGP internally. So I want RTG's traffic to go out Upstream 1, thats what I mean by preferred gateway.
Don't leak/distribute the full internet routing table into your IGP unless you want your network to die. Use OSPF for router loopbacks so your routers can find each other, and use BGP between your "internal" routers to distribute your own routes only - then only have the full internet routing table on your two "border" routers.