Platforms are always found with debris. It is handy that you can group the smaller pieces together to make a batch of 5 but the platforms are always something I have to leave behind. There were a few that were close to my base and I was able to balance them on my rover as I drove it back to the base. There is also the option to use a packager. Surely there is a better way to do this though. What is a good strategy to use to scrap the debris platforms?
This is a common problem people have. So far the game has put you in the mindset that your settlement is the central hub and everything has to go back here. The answer to your question is you cant attach large debris to the rover. The solution to the problem is different.
If you want to be able to gather scrap from all of the broken platforms around the planet, follow this guide to build the scrap garbage truck. It will let you bring the shredder to the junk so you can harvest a huge amount of debris without having to make constant trips back to the shelter.