Might be a stretch to find depending on where you live but there are a lot of smoothie places around here and they use monster sized straws so they can put real fruit, jelly, or tapioca in the drinks and not have to worry about the straws getting blocked up. They may be too big (have not seen or used the dse601) but by cutting a slice out of the side and rolling it tighter/cut off excess should work fine.
That's not a bad idea...
to give an idea how big the 601 cart is...take your 510 or 901 cart, and imagine the whole thing fitting inside the 601 cart, loosely.
The 601 is just a mm or 2 longer, but you could easily slide the 510/901 inside it. This thing is truly a monster cart.