You see power boats in the Bahamas with 'dinghies' (some 24' center consoles with immense outboards - being towed behind, in some cases as much as 200' feet behind. I guess it would work but you could lose it (need to wait for very nice weather to cross to the Bahamas or other open water trips) and it would slow you down. The fancier the
dinghy the more likely it is too be taken. In chancy areas we would always hoist ours to deck level with a
spinnaker halyard - no davits with vane steering. Yes there are thieves all over, in the Bahamas, Nassau is terrible for crime while Mayaguana seems perfectly safe.
Overall I would suggest that you compromise with getting the largest
dinghy/motor that will fit comfortably on davits. Always towing would be too restrictive in many areas including Bahamas and the Keys - for example, we had one squall on Abaco Banks in fairly protected water near Allans Cay with wave trains from north and south converging in quite chaotic ways. Would not have wanted to have a valuable
dinghy/motor being towed. We were towing our air floor
dinghy on this short (15 mile trip), but the motor and all gear were onboard.