Good, so the SXT link exceeds actual ISP internet speeds.
And the number of devices is so small that you can well do with a single /24 subnet.
Now imagine that you have instead of the 2 SXT’s, two Cube Pro’s, you are then allowed 
to call the link “wireless wire”.
If you do so, all you have (conceptually) is a single, cabled at 100 MB or so, local network, i.e. the same standard situation most people have in their homes or offices.
You can of course have all the fun you want with multiple subnets, VLANs and what not, but I cannot see any reason why a simple, normal, KISS, single /24 network with two gateways in failover wouldn’t work (you might want to decide which one is the primary and which one is the secondary, the DSL seems a little slower, so if you have an unlimited plan on the 4/5G and you don’t have congestion issues at certain times, probably the 5G is to be preferred).
Or maybe you want to attempt some form of load balancing between the two connections?
If you want people to be able to check your configuration and possibly give you some advice, Winbox screenshot are not the best way, you should post your configuration as text, a handy howto is here:
http://forum.mikrotik.com/t/forum-rules/173010/1