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