I WOULD ABSOLUTELY NOT check your scope. I too have a family, and am maxed on carry on space, HOWEVER, if you purchase a padded backpack (that’s what I did) or even a bag that you can pack clothes around the scope, that would be the only viable option in my opinion. Remember, that the airline takes no liability for damaged luggage. I check my tripod packed with clothes and that works well, but I would never check my scope. Too many problems…theft, damage, oh I shudder at the thought. Fly Southwest like I do. You get two checked bags per person free, and then 1 carry on bag up to 24 inches long. Put your scope in there if you can’t do a backpack. Get a hard side bag and be very careful with the eyepiece. I put sturdy foam between the eyepiece and optical tube when travelling.
Some people have checked the OneSky – mount and all – in the shipping box it arrives in. If theft isn’t a concern then that’s an option, though I’d add padding in the empty spaces. But considering you’re not shipping the mount you’d have to come up with something else. It’s sturdy enough to survive if it’s packed really well though it might require collimation once you arrive.
Checking in optical equipment completely safely is possible but costly. A Pelican case with foam customized for the tube would work, and you can put a sturdy lock on it. I know people who ship video equipment around the world for location shoots who do this with dozens of cases but when you’re shipping half a million dollars worth of equipment then the cost isn’t a big deal. But if this is common and the Pelican case is handy anyway it’s definitely the ultimate in protection.