Remoting onto a powerful desktop means you want 15" HD screen, which limits a lot your choices (especially with 128GB SSD requirement and 3lbs weight).
Have you tried this setup already with an existing laptop / desktop at your home? You'll need quite good Internet connection for "fluid" experience at both ends.
I used to remote in from my early 2011 Macbook Pro and it worked just fine. 15" isn't a huge deal for me, I agree that 1920 x 1080 would be ideal but it could be 13" and suffice. The connection where I am staying is reliable and on campus it is always constant to be able to be remoted in all the time. The weight could be flexible 5-6lbs or less is my maximum. SSD I thought would help speed up my operating system and help with the remote desktop. Thank you