I have a recumbent trike with Shimano e-assist and a Deore RD-T6000 long cage on a 11-36 ten speed cassette. The original front chain ring was 44T, which was fine for general flatland and some rolling hills. Before going to the Adirondacks for a bike tour, I put on a 38T front chain ring (and a new Shimano chain), which helped on the more challenging climbs. Even though I have a motor, I only use the lowest level of assist and I was pedaling pretty hard on every climb. I even broke a chain (which I had never done before). I had the tools to make the repairs, but I concluded I need an even lower gear for the steepest hills. Also, since returning home, I discovered that the chains recommended for e-assist bikes (particularly those with a mid drive motor) are built stronger than the standard chains. So I'm getting new chains, but I still think slightly lower gearing would help.

My derailleur is rated to work with the 11-36 cassette (according to the Shimano website), but I heard those specs are generally conservative. Does anyone know if my derailleur would handle an 11-40 or preferably an 11-42 cassette? Should I order a Wolf Tooth derailleur link when I order the cassette?

I'm sure I can get by without the upgrade, but I'm trying to do the bulk of the pedaling effort myself. I've never changed a cassette before, but I have the tools. I would hate to buy a new cassette if it won't work with the derailleur I have. My dealer is hours away, so this will be a DIY job, just me and YouTube. I do understand what the "B" screw does. Thanks for all advice, even if it's just keep what I've already got and leave well enough alone.