I added another cross tube to the end of the trailer frame. It was exactly 2" gap between the top of the receiver tube and the bottom of the frame wide flange beams (aka I-beams for you non-engineers). You could do the same and add the dual receivers. I tow my ~2800# jetski trailer with no issues.
Pic in the link below:
https://www.montanaowners.com/forums...3&postcount=10
It's been more than 3 years of use and it's solid.