What do you mean too many caluclations?
If your'e talking about scaling down the solar system, it's so easy you don't even need algebra, let alone geometry, trig. or calculas.
Start with the size you want the Sun to be and go from there.
Now in metric, I'd be at a loss, but in the English system is a total snap.

Lets say for example your Sun is 1 foot across. Again this is patheticly easy.
Start with distances and come back for sizes.

Mercury will be roughly 36 feet. Which will place Venus at 67 feet, Earth at 93 feet, and Mars at 1,42 feet. Jupiter 4,84 feet, Saturn at 8,87 feet, Uranus will be around 17,84 feet, Neptune 27,96, and Pluto at around 36,66 feet.
Now how did I do that? Bodes Law? No, even more simple then that.

If you are using feet for your scale, it is divideable by exactly one million miles for every foot. It's not entirely acurate, but actually more acurate then Bode's Law.

Now to make the sizes more meaningful let's make the Sun 10 feet instead. In which case multipy all your distances by ten.

Jupiter is 1/12 the size of the Sun, or 10 inches in this scale. Saturn is roughly 85% of Jupiters size, or 8 1/2 inches. Uranus and Neptune are each about one quarter of that, 2 1/8 inches.
Earth is slightly over 10% of Saturns size, or nearly 9/10 of an inch.
Venus is almost exactly 10% of Saturns size, 4/5 of an inch.
Mars is 38% the size of Earth, just over 3/10 of an inch.
Mercury is 3/4 the size of Mars, about 1/10 of an inch,
and Pluto is roughly half of that, 1/20 of an inch.

The moons Ganymede, Callisto, and Titan are nearly the same as Mercury.
Callisto slightly smaller, and the other two slightly larger.
Our Moon, Io, and Europa are about halfway between the sizes of Mercury and Pluto. Triton is a bit larger then Pluto. Then Titania, Oberon, and Rhea, and Iatepus, are just over half of Pluto's size.

It's a simple matter of knowing the relationship of each body to the next smaller body. It helps to have a good memory and an interest to begin with.
You can use that proceedure and totally amaze your teachers of how fast and acurately you can plot the sizes and distances.