Laptop for UE4 VR development

Hi, i have been working with Unreal Engine for a long time and i love it. Now i am working as a full time freelance working with UE4 in Archviz projects and VR. I have one question, i want to buy a laptop to work with VR, i have a good desktop ready to work as my main developer station, but i need a laptop that i may use when i have to show some project or modify something with the client or on the go. My budget is around 2000 or 2500 but if i can use less than that the better because i am also buying my HTC Vive and if i can an Oculus Rift too to use it with the laptop. I really like the Alienware and Asus ROG series.

So i will use my main desktop to model, create levels, textures, render, build light and the heavy work, but i would like to have a laptop that i can use to show the projects smoothly and modify projects on the go, or even work if i am on a trip or something.

Another question i have is that anyone had some experience working with laptops for this kind of tasks and if is better to have a more portable 15 or a 17 inch laptop that may be more confortable to work and if it worth to pay extra fo a 4k monitor, and i think it does.

Thanks,

Mauricio