1) will a U-Haul cargo van work?
Yup! Anything that can haul a sheet of plywood should do just fine!
The tank is 4ft long, around 2ft wide, so it and stand side by side will be 4ft x4ft! — sump can either stay in stand, or be placed separate of tank and stand!
2) what’s the best recommendation for securing it in transport?
I like to lay foam flooring or a packing blanket down under the tank/sump to protect them if setting them on the cargo floor next to the stand… then, ratchet straps only tightened gently, with hand towels or other padding between straps and tank! (I don’t like strapping over the top of the tank specifically, just preventing it from sliding! — you’d have much bigger problems to worry about if the tank ever endured a bump big enough lift it off the cargo floor in transit! [stand can get a strap or two over the top to prevent tipping])
3) What are tips you wish you knew when doing this?
— Figure out how much the tank weighs! If specs aren’t readily available, calculate the tank’s weight based off known dimensions and glass thickness… (a standard rimmed 180G is around 275lbs, for example!)
— Figure out your plan preemptively… make sure you aren’t expected to haul this thing down flights of stairs, or load it in a precarious steep driveway!
— bring a few cheap furniture dollies, rolling heavy stuff is always easier than carrying if the ground is flat and solid!
— always thoroughly check seams on a used tank for any signs of silicone peeling/etc! (Ideally request to see it full of water! You can pump/siphon the water off in <15mins while you work out a deal!)
— ask if the seller has any misc aquarium “stuff” they’d be willing to include with the deal if they’re getting out of the hobby, they usually just want it gone!