There is the 'Tactic' which is what you are doing, then there is the 'Technique' which how you do it. The 'tactic' is hard-fast and absolute. The 'Technique' is what is debated.
From WW2 FM-2-20 Cavalry Reconnaissance Troop, Mechanized (1944)
33. RECONNAISSANCE OF ROADS.
(skip part a.)
b. A road is observed by leading elements from successive observation points off the road. Detailed investigation of the roadway is accomplished by rear elements, or by leading elements when they have determined that the road is clear of enemy. Elements advancing on the road adopt formations which provide security, and offer poor targets to hostile fire.Dismounted patrolling may be employed to supplement observation from vehicles. Careful examination is made of areas in and adjacent to the roadway favorable for the use of mines.
That is the tactic, as far as technique, smoke is your friend. Smoke road parts to eliminate long range AT fire down sections. Leapfrog units down the road, move two hexes and pull off to the side, fire MG or HE into any cover as you move. You have stated a "Take this objective by 'X' time so a recon by fire would be a necessity, to quote "Elements advancing on the road adopt formations which provide security, and offer poor targets to hostile fire." Which is fancy speak for, "In a hurry, blast everything as you go." That is how you provide security and offer a poor target in a time constrained advance. You want formations that will be able to bring so much hurt on any opposing force that they might even decide to give up this position and pull back to a better one. In RL you can scare the enemy more than they scare you. That is a big part of training and experience.
You wanted to rule out supporting infantry but if a vehicle advancing is really worried about mines or enemy, dismounting a crew member to sneak ahead is a RL technique. In the game it would have to be the entire crew but a half-track crew moving ahead of a tank for spotting or mine purposes would be better than nothing.
If you want historical reading here is a link to a lot of US Army WW2 Field manuals. not all are downloadable but FM 17-20 Employment of Armored Units, Reconnaissance Platoon and Company is not only a fun read but really interesting illustrations. :
https://www.ibiblio.org/hyperwar/USA/ref/FM/index.html