As kwong2001 noted above, a small model is going to get very small, very quickly, in the sky if you fly it fast, which means you need to fly it slower and keep it closer, which means you need an engine with plenty of oomph to carry it into the vertical segments. So the YS 45 probably won't be enough engine for a small pattern ship.

A relatively inexpensive route would be to get a Venus and put a Magnum .70 4 stroke in it, or an OS .70 FL, or an OS .55 AX or Magnum .52 2-stroke. I use OS engines, but the Magnums are less expensive and seem to run okay. Lots of engine choices these days.

If you figure out how to fly precision with these smaller planes -- at slower speeds, dealing with the wind -- at the end of the day you'll be a darn good pilot.