Hello,
The set up you have sounds good enough for me. A dg would make life easier but is not essential. As for AH and VSI and even a turn co-ordinator they arn't really needed only take up more of room and weight. It doesn't matter if your doing a 25' 30' or 32.5' turn as long as it ballanced.
Having to many instruments can be a distraction for anyone who doesn't have the correct training to use them (ie Instrument rating) and besides we are day VFR only so not having them will stop you from being tempted!
My aircraft has a ASI, slip and alt.