I agree that you should start small and go from there, saves you money, and you can learn what you like and get only that.

In your list, you had some fuel tubing. I don't bring spare tubing to the field, but you do need tubing to connect the pump to your airplane and the fuel jug

Yes, you can wire up a resister to some leads to make a perfectly functional meter. If you use a digital meter, the whole "expanded scale" thing is not as important as it is when using an analog meter. I've been doing this for years.

The reamer and balancer are tools you should have, but don't need to bring to the field. Instead, ream out and balance your props at home.

On props, buy a few different sizes and brands and see what you like, then you just need to bring that one size in the future. But always have a spare or two with you.

I use after run oil in many of my engines, but I usually add it at home when I'm putting the planes away and doing post-flight inspection and notes.

A lot of guys bring screwdriver and hex driver sets to the field, I know I do (actually, I bring a few selected ones that actually go to screws on my planes). But if you pre-flight well at home, you may not need them much. In general, the more care you take at home, the less you need at the field.

There are guys at my field who come with a jug of fuel, a syringe or fuel bulb, a nistarter, and a chicken stick, and the're good to go for a day at the field. And there are guys who bring the whole shop with them, and always seem to need it.

(I acutally have two boxes, one that I always bring to the field, one that I bring sometimes. The second box has a lot of spare parts, like fuel tubing and other misc stuff. It's not necessary, but it's handy. I also bring redundant things to the field. I have two nistarters, since I am forever forgetting to charge one of them, and I hate it when they go flat. I also have a fast field charger that gets a lot of use.)