Best Computer for On-Site drawings?

I have a great desktop setup that works great with Softplan but I'm needing to do some on-site drawings for a remodel / addition job coming up.  What has everyone found that works exceptionally well for a new computer setup to use on-site that is plenty suitable to run the program?  Thanks!

Honestly i would save your money.  Get a tape measure, graph paper, pencil!!!! 

if you want lightweight and long battery life, get a surface book.  I used one for years for as built drawing.  I now use an HP Omen laptop because I needed much more GPU power for my renderings.  Little heavier and the battery doesn't last nearly as long, but it will usually last through an entire measure while I'm drawing the house room by room.

Thanks.  
Sam, did the surface book only accommodate 2d floor plans where you just didn't open a 3D model on site?  The first Softplan laptop we had when we started with the program in 2015 was an HP Omen.  It is just too old and slow now (by a lot).  Worked great when it was new though.   

the surface book has a pretty good graphics card...good enough for softplan 3d and enough I could run lumion but not great for lumion.  if the surface wasn't so expensive with a large SSD, I'd have one again