Returning to the USA for a holiday in late May I have a BA WT+ ticket (SIN-LHR-YYZ). This being the cheapest way to ensure a seat larger than Y and get enough AA Qpoints to seriously enable PLT requalification.

The problem:
BA flight scheduled to arrive YYZ at about 1505. Last AA connection leaves YYZ for ORD at 1835. BA and AA flights will be seprate PNRs and tickets

Questions:
1. Is this enough time to reasonably expect to clear customs/immigration and check-in. What's the risk?

2. If this is an iffy proposiiton (my current opinion) what class of AA ticket will allow me to attempt a standby if everything does work out? Note: I'm trying to get on the last flight of the day probably holding a ticket for the first flight of the next day.

Thanks

Happy wandering

Fred