It's southern but only receives two unfiltered hours of sun from 12 to 2pm, the rest is dappled. Next year going to remove a tree to get a little more sun.

Pictures of the entire area are needed.

Here is a photo of whole area, shirlpp:

It just seems like it would be awfully close to that tree on the right side. And....that tree on the right side seems like it's awfully close to the deck.

I think this is a little more realistic. (The vent pipe would not be much of a worry.)

shirlpp I agree it's not the best choice to put a large Crepe Myrtle there but we inherited the house like this. I already pruned the heck out of it in early spring. I probably took as much as four feet off the top! It was growing into the power lines. The previous owner didn't look at the size the tree could get. I'm looking forward to seeing the flowers. I found an old tag with the name Tonto on it.

Thanks for making that Yardvaark. I probably need to pull back the mulch line to create more space like your graphic suggests. As for the vent, besides my concern about hurting whatever I plant there, I don't want to block the vent and get carbon monoxide going into the house. I thinking of trying a small Zinfin there. For now I put some black and blue salvia on the sides since I didn't have another spot ready for them.

Transplant the crepe myrtle and move it to the left so that it hides what you're trying to hide?

https://www.gardeningknowhow.com/ornamental/trees/crepe-myrtle/transplanting-crepe-myrtle-trees.htm