2 Wan failover with prefered gateways for different deffault

Which way is the best and how to do this

Current network
T1 (with /24 block) → Sonicwall → servers and users Nat: 192.168.0.1

We’d like to add DSL or Cable and we only want the web traffic (PORT 80) to go through the CABLE/DSL any thing else should go through T1

the trick is if cable goes out we’d like to switch port 80 back to T1 for WEB browsing

Q1: should I use transparent proxy on mikrotik and place it between T1 and sonicwall or something else?

Q2: If I use Transparent proxy How do I set the failover I could not see any docs for failoverwithin MT for Proxy.

Thanks In advance
All input is welcome

ot except No it is not an option to replace Sonicwall