Very small layout and 42 curves?

I would think not, 42 inch curves plus 10 inches would place your oval at 52 inches .  You miss the 4 foot limitation.  Download one of those free trackplane software products, you should be able to plan it out to see what would happen.

Thanks, wondering if I just should have asked how I can fit 042 curves on a 4×5 layout and still have proper clearances?

I am assuming you intend to remove the straight sections.

When I was coming up with standards for my layout, I measured overhang on turns with various equipment. The worst overhang I found was 2.75", measured from the center rail. That was the horrendous cab overhang on a Lionel scale hudson. Oh ,and I tested this all on O36. Unless you are trying to run something really long, like E-8s or SD70s., I think the 3 inches of clearance that O42 will give you should be plenty good.

You will definitely want your track fastened down, so it doesn't creep closer to the wall when your back is turned!

You didn't say what track you were using, but since you mentioned MTH, I assumed it's RealTrax, so here's the best you can do with O42 curves. The rectangles are 3" wide to show the clearance you'll have.

Thanks a ton guys, I can see how I can do it now! I'll be a happy camper next Christmas!