Improve Inner-Join/Temp Table Query - sql-server

Question

I have this query and it's returning the results I expect, however, as you can see it's really crude & difficult to read.
I tried Inner Joins and FIRST_VALUE approaches but wasn't getting the right results so resorted to temp tables (just because I find it easier to verify results that way).
The issue is I get a StartWayPoint and EndWayPoint from dbo.Trips which is actually just the first and last points entered into the GPSWaypoints table (for a particular trip / vehicle).
Those points aren't entered in UTCTime order so I need to take the StartWayPoint, EndWayPoint & Vehicle, get results BETWEEN those waypoint values from dbo.GPSWaypoints table, sort that by UTCTime desc and the first Location string there is my true EndLocationString.
Hope that makes sense, I may have over complicated it ....I feel as though the answer is either an Inner Join or a SubQuery, my SQL skills aren't that hot though so any help appreciated.
DROP TABLE IF EXISTS #temp1, #temp2
USE XXX
DECLARE #StartWayPoint bigint, #EndWaypoint bigint, #Vehicle smallint, #TripId smallint = 9863;
SELECT t.Id,
t.Date,
t.StartWayPoint,
t.EndWayPoint,
t.Distance,
t.Alarms,
t.FuelConsumption,
t.Vehicle,
gpsStart.UtcTime as TripStart,
gpsEnd.UtcTime as TripEnd,
gpsStart.LocationString as StartLocationString,
gpsEnd.LocationString as EndLocationString
INTO #temp1
FROM dbo.Trips t
LEFT JOIN dbo.GPSWaypoints gpsStart on StartWaypoint = gpsStart.Id
LEFT JOIN dbo.GPSWaypoints gpsEnd on EndWaypoint = gpsEnd.Id
LEFT JOIN dbo.Operators o on Driver = o.Id
LEFT JOIN dbo.Vehicles v on t.Vehicle = v.Id
WHERE t.id = #TripId
SELECT #StartWayPoint = (SELECT StartWaypoint FROM #temp1), #EndWaypoint = (SELECT EndWaypoint FROM #temp1), #Vehicle = (SELECT Vehicle FROM #temp1)
SELECT TOP 1 g.Id,
g.LocationString,
g.Vehicle
INTO #temp2
FROM dbo.GPSWaypoints g
WHERE Id BETWEEN #StartWayPoint AND #EndWaypoint
AND Vehicle = #Vehicle
order by UtcTime desc
SELECT t1.*,
t2.Id as TRUE_EndWayPoint,
t2.LocationString as TRUE_EndLocationString
FROM #temp1 t1
LEFT JOIN #temp2 t2 on t2.Vehicle = t1.
Results from #temp1
Results from #temp2 (with TRUE EndWayPoint and EndLocationString

Answer 1

Think I've answered it for myself with a nested query, must have just had an error in my earlier attempts ....still open to suggestions for improvement though.
select t.Id,
t.Date,
t.StartWayPoint,
t.EndWayPoint,
t.Distance,
t.Alarms,
t.FuelConsumption,
t.Vehicle,
gpsStart.UtcTime as TripStart,
gpsEnd.UtcTime as TripEnd,
gpsStart.LocationString as StartLocationString,
( select top 1 (g.LocationString)
from dbo.GPSWaypoints g
where Id BETWEEN gpsStart.Id AND gpsEnd.Id
AND Vehicle = v.Id
order by UtcTime desc
) as EndLocationString
from dbo.Trips t
left join dbo.GPSWaypoints gpsStart on StartWaypoint = gpsStart.Id
left join dbo.GPSWaypoints gpsEnd on EndWaypoint = gpsEnd.Id
left join dbo.Operators o on Driver = o.Id
left join dbo.Vehicles v on t.Vehicle = v.Id
where t.id = 9863