I did a little more work on this part of the project last night.
I turned down a 1"pipe coupler with the thought that I could keep it short by turning it down and sliding 1/4" or so into the lower frame tube.
I knew that the step was very thin but figured it would help with alignment and give a couple more threads to seal. Started to clean the face up and...
It was thinner than I thought.
Didn't quite work out like I thought it would, but I think it still works. A 1"NPT x 1-1/4 Barb will be easily removed to prevent damage during motor install and will have plenty of clearance after install.