you dont always have to mount the rear sight as far back as possible, but its advised just because the longer the distance between the sights, the better, more accurate, shot you can take. its called, "sight picture" but.... where ever you put it, and zero it, it has to go back in the same place(flat top cut outs) if removed, or you will have to re-zero.
i started with a BSA red dot from walmart, cost around 30.00$. i thought that it was a good sight for plinking, and i could shoot very accurately with it. the problem that i encountered was that in bright sunlight, i could barly see the dot. now... the more expensive red dot sights do not have this problem. i.e. acog, aimpoint, bushnell, eotech.. and so on.
i would just place the dot sight right on the flat top of your rifle, and see how it lines up with your sights. if its to low, or you just want to raise it higher above your sights, all you need is a flat top riser. witch are also inexpensive. just be cousies to keep a good check weld. this aids in accurate shooting. if you think that the front sight is in the way, then you can purchase a flip down front sight, to co-inside with you flip down rear.
just remember as i said above, if you zero your red dot, and remove it, then re-install it, you have to make sure it goes back it the same cut outs it was origonaly zeroed in. this will yeild the best results.
i hope this helps, and if you have any more questions, just ask. ill do my best to answer them.
have a good one, brian
......welcome to the club. there is no cure for BRD!