A 6x8' table would be better for 28mm, but with the exception of Historicon, ALL of the games I've played have been on 4x6' tables Heck, I've played games, albeit small ones -
http://quindiastudios.blogspot.com/2010 ... mpire.html - on a 4x4' table). Here are a few suggestions...
1. Limit cavalry and artillery. For games of this size, I use half batteries if I use any artillery at all and cavalry 'detachments' of one or two squadrons.
2. Your scenario is important. Meeting engagements where both sides must march onto the table lend the illusion of a 6' wide table since you're not mucking about with the set-up. If your brigades arrive two or three turns apart, you are also not faced with crowding all of your battalions in one line!
Another tactic which lends itself well to this approach is deploying one army in a static position as the defender and having the attacker march onto the board, again granting the illusion of a wider table.
(Note: March on Columns of Companies... Columns of March take too many MPs to deploy into combat formations at this scale of action).
Again, if you design you're scenario properly, you could play a game on a 4x6' board down the length of the table. This may seem even more restrictive, but Napoleonic armies deployed in depth and actually attacked along a relatively narrow frontage, seeking to gain an advantage into which to send the reserves. You can simulate a small portion of a larger battle, say for an important redoubt or bridge.
I normally play games with 8-12 battalions per side (around 500 models total, I think), ranging in size from 24 to 36 models. Don't limit your choices to laying out your armies in two long lines! You get a much more exciting and fluid battle with some of the suggestions I've made here.
Do I wish I had a larger permanent table set-up? Sure, but you can certainly have fun with R2E on a 4x6' table!