Say you do a trip to the NE for a national level regatta at some place like Newport, Annapolis, etc, and you have four crew. Towing a J/80 at least a day and half travel time each way, you get there for 1-2 days of practice, 3-4 day regatta.

Fuel (3,000 mile round trip plus 200 miles while at venue), 8 mpg towing the boat - budget at least $1,500
Lodging at a nice VRBO for 5-6 days - $2k to $3k if you want something nice, half that for Super 8
3-4 days travel expenses (food and lodging, fuel covered above) - around $500
Food and drink during the regatta for four sailors - budget at least $200 per day so around $1,000 - $1,200
Round trip air travel/Uber for the two on your team who don’t ride up in the van or SUV - $1,400
Misc - I’d budget at least $400-$500

So you are easily knocking on at least $6k to $7k. Not too bad if your team shares expenses, a big investment for the owner if he/she covers all team expenses.