Planning for Spring: Have some ?'s

Stakes would work to start your plants but your going to need trellis or cages fairly quickly, if your looking for in-ground support.

There are stakes that would support a full sized tomato plant, and cages work for toms/melons, but there isn't enough soil depth in a typical SFG box to support the weight/size (indet toms will hit 8'+ with no problem).

You may want to look at string trellis techniques for your SFG tomato application (couple of very successul tomato growers on the forum use this) & cage or trellis for your melons.

I routinely do non-SFG 52" cage, stake and cage/stake combos for toms/melons, but only in a very heavy terracotta (9+" mouth & 12+" height). I've recently gone as high as 8'0" with stake/cage in a 9" mouth pot, but dont recommend it......it's a nightmare to keep cut/thinned so that it doesn't turn into a sail.
Your tomatoes will get top heavy very fast & anything over 52" height, without either a very heavy base, or 24"+ footprint (or fastened down), will end up on it's side with the slightest breeze. However, it's not a bad way to do the cherry, spoon or currant tomato varieties.

Again, the crook/loop stakes shown above are not a good permanent solution for the produce you listed in your post.