Your tree will need some space around it to grow larger. Planting something too close to it will take away nutrients and will shade your tree. Any pictures?

You can have it all; you will just have to fertilize more, as citrus are poor competitors and the nearby plants will steal the fertilizer.

How far away should I aim for to not disturb the roots too muck? Fertilizing is fine with me if I can have it all

As mentioned it will grow larger here is a photo I took in January of 2017 of one of my 20+ year old Satsuma trees

I have a Changsha mandarin tree in my weedsland and I have several other plants growing around it (American beautyberry, clover bush, Clematis drumondi, Ampelopsis arborea, coral honeysuckle and Sea Oats). It still grows fine and produces fruits every year. I’ll try to post a picture tomorrow if I find time.

Omar