@tjvoip45, thanks for your suggestions - we always appreciate you being so active on our Forums!
This can actually be accomplished without any VLAN requirement. The first thing you would do is create a DHCP reservation for the one computer and then create two outbound rules:
Source: DHCP reservation IP address
ISP 2 (LTE)
Check the terminate sessions on link recovery
And then below this rule you would create another one:
Algorithm: Enforced to WAN1
This rule must be placed below the other rule or it will not work.