First, maybe a bit nit picky but I don't think a typical hard
dinghy would technically qualify as a lifeboat. Might be a backup for a
liferaft and, if unsinkable maybe a primary option but as designed anbd built these are primarily dinghies.
As far as placement, I think it is a more an issue of where it will fit on the
boat more than the best place. On a cruising boat that size you have two options.
If the "lifeboat" is not too heavy you can hang it on
davits.
The only other place to put it is on the foredeck in front of the
mast.