If you want to use the drawknives again but don't have room for a shave horse, I've seen some smaller alternatives that look interesting. You might be able to clamp them onto a railing or something for stability while using them.
One is a shave pony. It looks easy to build but you do still need a little space for it.
The other I cannot seem to find again on the web but it was essentially a small version of a riving brake: riving brake http://pfollansbee.files.wordpress.com/2008/08/riving-break-2.jpg?w=300&h=200 It was made out of a couple dowels and clamped to a workbench (or railing in your case). You don't need the big A-frame shape just the two horizontal pieces to jam the wood between and lever against. I think this concept is the winner for utter simplicity.
