Doing full body workouts for each workout you shouldn't run into the standard bodybuilder plateau effect. The point and focus of your workouts is strength and muscle endurance not mass and definition. You are not power lifting and going for massive weight and this is really the only time this will come into effect.
As for making your own dumbbells that may be difficult... I would reccomend using kettlebell type weights which can be filled milk jugs or something similar and honestly with the TRX if you got a weighted vest or have a decent backpack and added weight to it that would be fine for most things. I can think of VERY few exercises where you are required to have dumbbells. Between weighted pullups, pushups, dips and situps you can hit most upper body muscle groups. Mix in some TRX exercises with weight or even higher resistance bodyweight, sled pulls and pushes, log presses and lifts, tire flips and sledgehammer smashing you should hit all you need strength wise. A majority of your workouts that you will want to do are plyometric and explsive anyways so you wont need or want a ton of weight.