I don't know what time your flight to Caracas would get in but if it is before 3.00pm then it is possible to fly to LR the same day.
Los Roques airstrip has no lights so it closes down when it gets dark. That means that the latest flight from Caracas is at about 5.00pm.
I have also stayed at a couple of hotels quite near to the airport and also some others in Caracas itself. Caracas is about one hours drive from the airport. I understand that it is not safe to walk the streets but the hotels are OK.
When you land at Caracas airport it is good to have someone meeting you who has arranged ground transportation, hotels, flights etc. I use a really nice Swiss-Germany guy called Hans- Peter Zing.
If you need details of any of this stuff, send me a PM.