Hi, Welcome. That viv size would just about be big enough for two adult Leos - but in a viv that size there really is not much room for them to get away from each other if they feel they need to and it would be difficult to get enough hides in there. You should always have a spare set-up (needs only be a plastic rub, heatmat and stat - you can improvise hides and dishes) in case they need to be separated in a hurry. There are many reasons that you may have to split them: They may not get on, one can be getting all the food, one may be dominated / bullied by the other, one may become ill and so they would need to be separated - sometimes at very short notice! Also I'm sure you know that you can't keep two males together (nor a male and female ideally - certainly while juvenile) so unless you are buying them at an age where you can determine the sex then be prepared to split them. Having said all that 2 together can work well - just be prepared to split if needed at short notice.
For the trip I would put a bit of kitchen towel in the bottom of cricket tubs, put one Leo in each, then use a polystyrene box or cool box with a hot water bottle(wrapped in a tea towel and not too hot) in the bottom. Or if you look on-line you can buy heat packs instead of hotwater-bottle. A couple of times through the trip I would open the box briefly to let air in and check the temps. Good luck and enjoy your little ones