Plumbing Rough In

We are remodeling our bathroom in an old house (1922) and didn't pay much attention to the rough-in of the toilet when we removed the old one or purchased the new one. We're putting in the toilet, but realized there is a 4.5" gap behind the toilet, which looks ridiculous.
We love the toilet (Kohler Memoirs), and would like to know what our options are for fixing this issue. Purchasing a 14" rough-in toilet still leaves us with a gap of several inches behind the tank in a small bath (plus there aren't many good-looking options). Is there some kind of conversion kit available? Is it a huge deal to move the drain closer to the wall (even though we just had the floor tiled) - something a plumber could do without costing us an arm and a leg?

While you have everything ripped up is a fine time to make this old rough in nice once and for all!.....Just tiled! Awwwwww.A nice shelf over the tank will hide things then.

Unfortunately, the toilet really hangs out too far into the center of the room (it's a small bathroom.) Anything we can do to get it closer to the wall would be better.
If we have a plumber come in and move the drain/flange, etc., approx. 4" is there typically enough room to the edge of the toilet that we wouldn't have to fix the new tile?

The only way to move the Kohler back closer, is to move the drain.

Only Toto has the option of moving the bowl back 2"

Retiling a small area doesn't sound to bad to fix a situation right. Do you want to live with a toilet almost ridiculously out in the bathroom for years?

While that toilet may look good, form doesn't always follow function...I have problems with Kohler anything.

On a normal toilet, if you measure from the bolts holding it down to the finished wall, that will tell you the rough-in (this doesn't work for all toilets! - then, you have to pull the toilet to measure the drain). Standard in the USA is 12". The only other standard choices typically offered are 10 or 14", and typically, it's the same bowl with a bigger or smaller tank. As Terry noted, only Toto offers the same toilet (on some models) that can be made to fit on either 10, 12, or 14" rough-ins. The others, just leave the bowl sticking way out there, and use different tanks to fill in the space behind.

It sounds like yours is much greater than the largest available, at something larger than 14".