Come on. it’s just a couple of sprinkes of water on your head. If you drown from that, it’s probably a sign from above anyway 
(Seriously, baptism is highly dependant on the church in question. My church feels that infant sprinkling is OK, but I know a lot of people who would have strong words against it. )
**Thing is (as I understand it) I would have to be baptized in order to fully receive the kingdom of heaven. **
Umm, nope.
Where would you end up if you drown during baptism?
If the church people let you drown in a full immersion baptism rite, then you ended up in the wrong religion. If you drowned you ended up dead.
In full immersion baptism, when you put your head underwater, is when you officially get baptized. I would assume thats when you drown so it means you go straight to heaven.
If you trip and fall outside at the church, i hope someone has a bucket to perform the last rites and its a good thing the RCC** only uses head sprinkles.
If you died the night before the rite, you stay at limbo, which is pretty much Hell but for only a short time (until the world ends)
If you masterbated before dying at the night before getting baptized, youre going straight to hell. 
I love how the Roman Catholic Church is referred to as the RCC. Sounds so secret agentish… The paramilitary shock troops of the RCC will perform an EBR (emergency baptismal rite) on any person found dying within their area of jurisdiction. I wonder if they start spinning around and a cassock appears on them along with a bulletproof bible and the golden rosary beads of truth. 
*
That’s an exellent point, but the theif was saved becasue he had faith in Jesus, as we are, not because of any baptism or lack thereof, nor because of the OT rules, as he was curses, since anyone who hangs from a tree is cursed, so it has to be by faith.
Indeed, as is everyone from Adam until the end of time - the OT believers looked forward to His sacrifice just as all those afterward (ourselves included) look(ed) backward.
Well, on the standard of some groups, faith in Jesus is all it takes, so the question becomes moot.
Addressing it, therefore, from the catholic perspective (small “C” to include other groups that believe in sacramental baptism, in addition to the RCC), there is, actually, an answer to the question.
It’s expected, of course, that anyone who comes to know the saving grace of Jesus will present himself for baptism, if he has not already been baptized as a child. However, the church takes into account that things may intervene to prevent it. Therefore, there are two categories of “constructive baptism” if I may coin a phrase, equivalent to the regular ceremony:
[ol][li]Baptism of blood. If you are martyred for the faith, not yet having been baptized, you are accounted as having been baptized by the blood you have shed for Christ.[/li][li]Baptism of desire. If it is your intent to be baptized, but through no fault of your own, you are unable to do so, as in being an isolated convert hundreds of miles from the nearest other Christian or dying unexpectedly prior to the date set for your baptism, you are considered as having been baptized by the intent you had to be baptized. If it was your will to be baptized, the lack of having actually gone through the ceremony is nothing to the God who looks into men’s hearts.[/ol][/li]
Certainly the latter status would apply to a person who died up to the instant when he was baptized. And death is almost never instantaneous, especially in a case of drowning. The person would remain alive, though dying, long enough for the official formula to be completed – it’s only one sentence long, after all – and thus would have been baptized as he died.
Since baptism wipes away all sins, according to Catholic theology, it almost seems like the best of fates from a Pascal’s wager perspective to drown during baptism!
“Baptism of blood” and “Baptism of desire;” jeeze, I’d forgotten those phrases! The memories of fourth grade come trickling back!