Is there a tow available to the Basswood River entry point?
I would like to start there and head downstream into Crooked and all the way to Iron lake and get a return tow from Bottle Portage.

Any suggestions or experiences?

No. There is a section of Basswood Lake (like from around Lincoln Island to the narrows of Jackfish Bay) in which motors are not allowed. Your best bet (if anyone still offers the service) would be a tow from the end of the Fourmile portage to the termination of motor service on Jackfish. If you're planning a Quetico trip you would have to check in at the ranger station prior to heading back to Winton for the tow (better to do it in reverse starting at the Bottle Portage in that case).
Motorboat routes

Fourmile portage is petty much closed. You need to get a tow from Prairie Portage. The tow will take you as far as motors can go. Washington Island and you have to paddle from there. 7 ish miles. I would use La Tourells for a tow. They can also tow you to Prairie Portage.

The best option is a tow to Back bay portage. The portage connects to Pipestone bay. That’s where you start paddling. LaTourells along with anyone else can do it.