Alternatively and as temporary solution, a mod about leaving the reticle visible only on horseback and when the bow is used. On foot with all other weapons, the reticle have to remain hidden so you'd use ADS for better immersion in FP IMO.
I tried playing without a reticle and it feels great, but without ADS on horseback and some kind of a guidance with the bow the game becomes almost impossible. You can't shoot a single dear with the bow without the reticle, at least I wasn't able. Let alone shoot it with the bow on horseback... something that is very easy in TP and with reticle. For realism, shooting on horseback shouldn't be easy to do (it is actually very hard), but for gameplay purposes it is clear Rockstar didn't intended players to shoot the bow and other weapons from the horse without a reticle. It's a pity, because if there was ADS and/or some mechanic specifically for that the immersion would'd been amazing.