From reading the previous posts - it looks like the decision has been made… but thought I’d chime in with some related experience.
A few years ago I was in a similar situation and decided I wanted a laptop capable of allowing me to do CAD and renderings “on the road”.
I thought that I was going to do a lot of work away from my office/home so I bought a top end Dell 17" laptop. Can’t remember how much it was - but it certainly wasn’t cheap.
I now rarely use it as it is so heavy, doesn’t fit in any standard laptop bags, the power-supply is huge and the battery power drains quickly when used at full tilt. I could also cook an egg on it after a few minutes 
I despise having to lug it around when I do actually need to.
In short - to be really productive with CAD you need a great (large) monitor and a mouse - 2 things a laptop can’t offer (at least while plugged in at a coffee shop)
As mentioned by others - get yourself a great (and expandable/updatable) desktop and a nice portable laptop to use with presentations. You’ll be set.
RJ