I've done rips of 2x8s down to 2x4 size with the TS55, clamping the rail to another board along side the board I was ripping, and wouldn't hesitate to try it with some bevel. The first time I tried 45 degrees I'd want someone else there to help hold things for the unexpected, and I'd play with ways to hold the trim against the makeshift fence, but as long as things are clamped so that you can have both hands free to hold the saw down on the rail (because, at a 45 degree angle, it will want to fall off unless it's held) I don't think you'll have a problem.
I should note that I was particularly impressed with my most recent ripping attempts because pre-Festool I'd ripped a 2x4 in half at about a 15 degree bevel with a Skilsaw and another 2x4 as a straightedge, and a helper and lots of clamping, and I managed to generate a heck of a lot of smoke and leave saw marks and scorched wood everywhere. Recently with the Festool saw I trimmed down 2x8s to about 2x4 (I needed some 2x4 sized stock that was very straight, so I took slices off either side to let the wood relax) by myself, with two rails joined by the rail connectors, and had beatifully finished edges with no saw binding whatsoever.