I'm imagining, and as things stand, my imagination is hinting at crappy battery life due to lack of tuning.
But if you want to try, Solaris was forked long ago -- Illumos is out there.
http://www.shrubbery.net/~heas/sun-feh-2_1/Systems/Sun4c/SYS...
And the bizarre quazi-portable-but-definitely-not-laptop SPARCstation Voyager:
https://www.youtube.com/watch?v=Z2CprTGEIS8
http://www.tldp.org/HOWTO/SPARC-HOWTO-5.html
http://www.kevra.org/TheBestOfNext/ThirdPartyProducts/ThirdP...
http://www.ebay.com/itm/WORKING-Rare-SUN-Voyager-SPARCstatio...
http://www.shrubbery.net/~heas/sun-feh-2_1/Systems/SSVygr/4m...
https://en.wikipedia.org/wiki/Cobalt_Qube
https://en.wikipedia.org/wiki/Cobalt_Networks
[1] Sun's buy of Cobalt had bad timing, since the dot-com bust happened soon after.