The slotted plywood is the most stable, and easiest to transport as far as 'stability to easy-of-transport' ratio. 4x8 foot plywood, cut in half, slotted makes two Xs that you sit under the TC.
You should not need any additional boards for your short stay, just sit the TC on the Xs directly. At home I do put 3/4 inch shelving planks across to provide a lot of flat surface for the TC to sit on, but tat is for long-term parking.
I use 3/4 treated plywood for home storage, and sit small 2x4 scraps at the edges to keep the plywood out of the water when it rains. For your short-term purposes I imagine a thinner board will do, ยฝ inch or even 3/8 plywood (or osb) since the camper jacks will still carry part of the load. The plywood X is really to just give a solid base, to keep TC from wobbling, and to help support the floor while out of the truck, so it is not necessarily needing to carry all the weight of the TC.
Best thing is that you just lay the plywood down in the truck bed and plop the TC on top of it for travel. You may need another rubber mat - one on bed, one on the wood. I have not tried sitting the camper directly on the plywood. Maybe, because the wood grain has a lot of friction, it would not slide much without a mat though. I do not knowโฆ
If you have an 8 foot bed, then perfect, if a shorter bed, then cut the X pieces so they fit in the bed. For a 6 foot bed you would have 1.5 foot tall Xs for instance, assuming the TC can lower that far down.
Consider that the plywood might be able to extend past the end of the truck bed with TC loaded, it just depends on the under side of your particular TC.