TLP175A High Load alternative
Is there [...] a tool that will help me search through the alternatives in future


You can use distributor's sites to search for such optocoupler/solid state relay:

Search for TLP175A on e.g. mouser.com, find which product group it is in.


  All Products  Opto-electronics > Optocouplers/Photocouplers > MOSFET Output Optocouplers > Toshiba TLP175A(TPL,E)


Click on MOSFET Output Optocouplers and use the filters to narrow down the result.
(and you'll find Mouser doesn't have it)