Well it sounds like the rocks might be a really good idea in some instances, but I think for now my best option remains with the steel screw anchors. My main concern with those is the weight. 10 stakes will probably end up weighing about 25 lbs, which is half of my checked baggage allowance. I could go with something lighter weight like the plastic Orange Screw: https://www.amazon.com/Orange-Screw-Ultimate-Ground-Anchor/dp/B01B26DHAU/ref=cm_cr_arp_d_product_top?ie=UTF8

but I suspect this may snap on me and I'm not sure it's worth the risk.