I would not amend the soil at all, unless you are prepared to amend the entire bed. If hardy bananas overwinter reliably in your area just plant it in the native soil and save your compost for mulching and forget the perlite altogether. Th hole needs to be as deep as the present rootball and wide enough to spread the roots out.

We planted them today as seen in this phote. Not a whole lot of root could be gathered but some visible roots. One far right and other left right in the shadows. Both locations should receive 6 hours of sunlight in spring and summer. Remved all the lower leaves and size of top leaves to reduce evaportation. However, the right location is not draining well at all. So I added tons of compost over the root ball. Hoping it will be okay if not I may have to relocate it. No perlite was added, only native soil and compost. Plan to water both atleast once a day but I am wondering about the drainage also. It is going to be in upper 80s this week and next.

How soon can I tell, plants is not wilting due to water drainage issue for the right plant ? The left plant has good drainage.